There are times when you want your printer to stop printing, let you insert magnets or some other goodies into the print, and then continue printing. This approach gives you a sleek way of embedding various "foreign" objects into your prints. However, the user experience of such activity is often sub-optimal. While you have even muddle through the task with a filament change command, I wanted to make adequate support for such actions.

There is the M601  G-code that PrusaSlicer can insert for you. But that approach does not work with Octoprint, and I don't know why (M600 color change works without any issues). But even when while running from SD card, the M601 experience is suboptimal, as can be seen in the comment section of the Prusa Knowlage Base.

Here is a video of the improved magnet insertion that I envision:

and here is a G-code that approximately does that:

M300 S150 P300; beep
G91 ; relative movements
G1 Z5 ; Z up 5mm
G90 ; back to absolute
G1 X10.000 Y200.000 E0 F3000; park
M1; pause

M105; reheat?
G28 Y; home Y (in case the intervention shifted it)
G1 X10.000 Y10.000 E0 F3000; park for priming
G91 ; relative movements
G1 Z15; Z up 15mm
G90 ; back to absolute
G92 E0; reset extruder
G1 E30 F150; prime
G92 E0; reset extruder
G91 ; relative movements
; M300 S150 P300; beep (does not work as expected)
G1 X2.000 E0 F60; 2s move
G90 ; back to absolute

The first part is simple:

• beep, to get the user's attention
• move the extruder 5mm up;
• park it in the back left corner of the build plate;
• pause the print.

At this point, we have easy access to the printed object. The print has to be resumed from Octoprint, though. It would be nice to resume prints from the printer's menu, but I didn't figure out how to do that yet. After resuming, the following events occur:

1. first, we use M105 to return the printing temperature? I saw this G-code often in other approaches, but honestly, I don't understand it. As for me, the temperature of the hot ent is stable through the whole process, but remove this command at your own risk;
2. we home the Y-axis (heat bed), as our manipulations with magnets could nudge the bed a little bit;
3. we park the extruder in the front left corner and move it up by 10 more millimeters;
4. the printer extrudes some filament to ensure that there is no air pocket left after the filament oozing out during the pause;
5. there is a short 2 seconds movement along the X-axis to indicate that the extruded filament should be removed. I tried to beep here, but as a result, that beep occurs imediately when resuming the print…

After all these steps, the printing continues.

Of course, many improvements can be made. If you are going to run this close to the top of the printer's build volume, the extruder will crash when rising. It would be good to have beeps upon purging. It would be good to cool down the nozzle during the pause, re-heat it, and prime. But I think that this is already an excellent first step. You can just paste the code into the "Add custom G-Code" action of PrusaSlicer.

But ideally I'd expect that M601 could work like this.

Originally I planned to write a completely different story, but one event changed everything about a week ago. If you follow this blog closely, you may have noticed that I mainly use an Original Prusa i3 MK3S for my projects. I like the Prusa Printers company: besides engineering high quality open-source 3D printers, they are also pretty much engaged with the community around them. During the COVID19 times, Prusa were fast in developing a new way of working to protect their employees. They were also a highlight at the widespread practice of printing protective shields for medical workers. At the same time, Prusa representatives stopped going to events around the world, which resulted in some drop in communication and showcases of their new products.

One week ago, Prusa 3D hosted a live stream where key persons talked about the latest news. I tuned in to that stream without much motivation: I was tired and still had to finish some work-related stuff. And then, one minute into the stream, Mikoláš Zuza (the guy behind most of Prusa videos) shows a contact lens case that I designed (remixed to be precise) and talks about how helpful it is.

This was one of those awesome feelings that I experienced in my life. I was especially surprised because I designed the case only with my own needs in mind, but then decided to share it with other people because "why not?" In the rest of this blog post, I will tell a short story about how the case. And if you want to watch the whole stream, it's available here:

Sight Correction

The fact that I have a poor sight came to me as a surprise when I was doing a regular sight check required for a driving exam. I never had perfect sight, but the test that checkups that I did two years earlier showed that my sight is about 80%. Now it's around 40% because of astigmatism. Essentially, my eyes are not perfectly round, so light does not focus on a point at my retina but rather in a segment. That's why everything that I see is slightly blurred. Each eye is deformed in a slightly different way; that's why they blur what I see under different angles. A human brain is an outstanding machine: it can take two distorted images (that come from the eyes) and create a refined version better than the two originals. At the same time, the brain works very hard each time I look around, so I had frequent headaches.

I got glasses, proper glasses, expensive glasses. Disclaimer: there are no cheap glasses in Switzerland, only expensive and very expensive ;). Glasses did their job: I could see everything razor–sharp. At the same time, the glasses squished everything that I saw. And even after I got used to the squishing, I had a hard time figuring out what happens on the edge of the glasses. For example, running (on the stairs) was super-complicated. Then during a vacation at my home town in Ukraine and got contact lenses. They are my saviors, I put them on in the morning, and I try not to forget to take them off when I go to sleep. I use monthly lenses because they are cheaper, but I also have some daily lenses "just in case." I keep a couple of pairs in my car, so I can always fix my sight when I have to drive. I keep a couple of pairs in my backpack as a backup if I forget to put on the regular lenses. But hey, it's a good idea to keep the lenses together and distinguish left from right. That's why I needed a case.

Making the Case

First, I searched for available designs, but I couldn't find anything. Then I looked for the available design of parametric cases. And I found a Customizable Case (Rectangular) by walter at Thingiverse. This model is a simple rectangular case with rounded corners. Its lid is attached permanently to the body with a thin, flexible hinge, and stays closed thanks to the friction. So it's a single solid object, and simplicity is priceless.

easy to set a correct size to fit four daily contacts (two stacked pairs). I also added a divider in the middle to ensure that the left and right lenses won't mix. I added L and R letters to the lid to make it even more apparent which lens corresponds to which eye. Finally, I spent quite some time fine-tuning the hinge, and the lip that keeps the cover closed thanks to friction.

You can also make the letters truly pop by doing a color change at the level of letters while printing. This also results in a nice design with top and bottom in one color and walls (and the letters) in another one.

Epilog

That's kind of all that there is to the story. I printed a couple of cases to put in my car and my backpack.

Now when I travel for a couple of days, I put on daily lenses at home and trash them at the end of the day at a hotel. Next morning I will put on other dailies from a case that I printed, and it's always a pleasure to look at it. But it's also another kind of pleasure to know that this case is useful for other people.

With this post, I'm starting a new category called blitz. This category will contain 3D-printing projects that are fast in execution and are performed in somewhat urgent circumstances.

I'm subscribed to Curiosity Box — a service that sends you a box full of geeky awesomeness four times per year. The last box that I got had a drinking bird toy/experiment.

Sadly, one of the legs of the bird was missing. Now that was a bummer. I  twitted about it, and soon the official Curiosity Box account responded and promised to resolve all the problems.

I did not doubt that the Curiosity Box team will send me the missing leg, or even a new bird. But I already told my daughter that I would show her an exciting drinking bird, and it was very annoying that I can't do it.

But then I thought: "Hey, the legs are simple shapes made out of plastic, and I have a 3D printer that prints plastic." So I took a photo of the available leg, imported it into Fusion 360. Then I sketched up something over the imported canvas and extruded it to the correct thickness. The print took only 15 minutes.

That was it. I had the missing leg after about half-hour of modeling and printing. And it works as well as the original.

The Morale

The Curiosity Box team contacted me on Twitter in one day and told me that they could assist me with this problem. But I already have a working bird… I thought that it does not make sense to send something now and waste our world resources if I don't benefit from it. I thought about asking them to add the leg to the next box that they will send to me. But again, I have a working bird. And the original injection-molded part is not much better than the one I printed. Moreover, if I use this bird a lot, I can print epic muscular legs that are way better then the original ones. And I can make a base that includes a water reservoir on a perfect distance next to the bird.

I think we are still far away from the age where 3D printers are as reliable and affordable as are currently the 2D paper printers. But imagine if one day you didn't have to ship tons of plastic around. You would ship essentials and send 3D models over email. Edelkrone is already doing that. Check out their ORTAK products.

At the moment, I'm in time between two Easter celebrations. The one where I live now — in Switzerland happened last Sunday. And the one where I am from — Ukraine, will happen next Sunday. I was busy with preparations, and also I launched a 3D printing channel on YouTube for Ukrainian-speaking folks. Thus this post is going to be on a short side, but also a festive one. Since I got into 3D printing, I'm printing an easter egg every year. Here are the three eggs that I printed until now.

My first printer was the Neva by a French company Dagoma. I can say many bad things about that printer… Most importantly, though, it was a printer that I took out of the box, and it printed me a good quality benchy. It's a printer where I printed my first functional models and OpenScad designs. Some of those designs received a lot of attention on Thingiverse, and so I kept going. I tried printing may different easter egg models, but only one printed successfully. Ok, maybe "successfully" is an overstatement, but this was the only one that printed completely. My daughter likes it very much.

My second Easter egg was printed already on an Original Prusa i3 MK3. That year my main goal was to print the Torture Egg by Maker's Muse. It's a challenging model to print, but it's also a beautiful design. I managed to print it in a lovely pink filament, but since then someone dropped it, the egg broke, and I trashed it. Now I can present you another egg that I printed during the same year.

This year I printed something special. It is also an egg by Maker's Muse, but instead of being a torture for a printer, it's a puzzle for a human. I encourage you to watch the video about this model. This year is different — we won't go to church for Easter with our family; we won't take an easter basket the newly printed easter egg. And while the puzzle egg would look like an abomination in an Easter basket, it served very well as a gift. I three extra puzzle eggs and gifted to others.

After one of the significant rearrangements at our home, medications ended up in an easily accessible drawer. Needless to say, we wanted to limit access to the medications for children. As the drawer was from IKEA, we also found a simplistic catch manufactured by the same company. The product's full name is PATRULL Drawer/cabinet catch, and I especially like it because the whole locking construct is inside of the drawer. When we wanted to buy this item, it was out of stock at the closest IKEA store as well as the official IKEA online shop. Nowadays, this item is not available in Switzerland at all. So what would you do? I decided to print it.

The Setup

First of all, I had to model the drawer catch. Of course, I could design a unique model, but I decided to re-engineer the design of IKEA. This project is not the first clone that I created. Still, for all the previous projects, I had the original item at my disposition. Not being able to look a the item from every angle and measure every dimension poses a big challenge. Luckily for me, the drawer catch is a relatively simple model, and IKEA has a very lovely policy about their manuals. Each product has one or more assembly manuals that follow the same design, and all of them are available in a PDF format for free from the official IKEA website. On the first page, each manual has a picture of the product. I used the first picture from the drawer catch manual as my primary guide.

I needed to see the image-guide all the time and be able to compare my 3D model with it. I used the LayerX app for Mac do display the translucent image from the IKEA manual over the OpenScad app. I believe there are many similar apps for other operating systems.

IKEA manuals use orthogonal projections to depict items (i.e., the projections are not distorted because of perspective). This is helpful as you can also use the orthogonal projection view in OpenScad.

The next step was to decide how basic properties relate to each other in the actual model because a projection always discards some facts. I assumed that the attachment plate of the hook-part is a cuboid with a cutaway. And that the hook rod is perpendicular to the attachment plate. In other words, here are some basic properties that the following picture satisfies:

• a* lines are parallel
• a¹, a², b1, b² are on the same plane
• a³, b³ intersect on a plane parallel to the plane of a¹, b¹
• b* are parallel
• b* are perpendicular to a*
• a¹ and c³ are on the same plane
• c* are parallel
• c* are perpendicular to the plane of a¹, a², b¹, b²

Modeling In OpenScad

A useful trick in OpenScad is to hardcode the camera position. This way, each time you when you preview (or render) the model, the camera is placed in the same location. There are 3 special variables: $vpr (viewport rotation), $vpt (viewport translation), $vpd (viewport distance).

The rotation vector is the most important one as it defines how the projection is constructed. For me, it was equal to [65,0,45]. These are nice numbers because IKEA constructs the projections for their manuals under clean and well-defined angles. The last coordinate of 45º defines rotation around the (vertical) Z-axis. As a result, we end up looking from an equal distance between the X and Y axes, and this explains why b* and c* lines have mirrored properties in the above diagram. The first value of 65º defines the angle from the Z-axis. In this case, 0º means that we look straight down, while 90º means that we look from the ground level. The middle 0º defines the rotation around the viewing axis (this is what happens when you tilt your head to the side). You can't change it by moving the camera with your mouse, and you won't need it for the most common use-cases.

Viewport translation is represented by three coordinates that define the point at which the camera is looking. This value is useful for centering your models in the viewport. Finally, the viewport distance variable is just a single scalar value that defines the zoom level. There is no need to get all the values by trial and error. You can set up the view with your mouse and copy the viewport values from the bottom bar of the OpenScad window.

One important thing during 3D modeling is to print your prototypes often and test if they work. I had some misalignments, but it's just a rough prototype, so I printed it and discovered that what I did doesn't make any sense…

The hook was not going out of the drawer far enough to catch anything. When I investigated available photos and diagrams more carefully, it became apparent that the hook's rod is not perpendicular to the mounting plate. Instead, it's inclined in the direction of the hook's "tooth."

So I went back to the drawing board. I had fewer constraints now as I didn't know the inclination angle of the hook. Thus I decided to recreate the mounting plate with more precision and then determine the angle from the diagram. My second try was much better, and here you can see the final version.

Some parts are still not perfect. For specific curves, it was too much of an effort to make them the same as on the drawing. I also made some holes smaller to fit my screws better, but ultimately it worked.

When cloning objects based on their pictures, there is one final step to do — scaling. We can make a dimensionally-accurate model, but in the end, we need to make sure that the scale is comparable to the original. I did this partially by correlating sizes available in the manual and partially by printing the objects, seeing if they work in the physical world, and adjusting the scale.

I printed the designed objects in PETG because of its flexibility and impact resistance. Also, I printed it in white, and this is awesome. I like the white color that matches the drawers, but the original items were only produced in black.

The Morale

First of all, I have a catch that stops children from accessing the drawer with medications. Secondly, I have a model that I can modify if it does not work well in a particular situation. For example, after some time, a child may learn how to open the drawer. Then, to complicate the access, I can mirror the model and attach a second catch on the other side (this would not be possible with the original IKEA item).

I shared this story with you, and I hope that now you have more ideas on how to use OpenScad and how to redesign existing objects without having them at hand. I also hope that this post was entertaining for you.

I have no clue how does this all fits into the legal field. I won't share any models, as I believe that this can violate the intellectual rights of IKEA. But I don't know if I'm allowed to do such clones for personal use, and if I'm allowed the share such information with you. If I listen to my moral sense, I think that it's okay. In the end, I made an item of inferior quality, and even if I wanted, I could not buy it anyway.

For the last seven years, our family lives in rented apartments (and before that, I was a teenager living with my parents). When we moved into our latest apartment, I was immediately annoyed by screw holes with anchors in the bathrooms. Come on, someone drilled the holes, and I have to follow that decision? And it does not make sense to drill new holes, because then I will be responsible. And the old holes will be there anyway, and they are ugly.

On the other hand, there are already screw holes in the walls. They are next to a sink and a bathtub, so they are meant for towel hooks. I can reuse the holes, and then I will have towel hooks, and I won't be responsible for drilling the walls. The only restriction that I had is to find hooks that have the same spacing between the mounting holes. So I went to a local home improvement shop and discovered that all the hooks have holes that are not suitable for me. There was only one ugly plastic hook for $15 that could match the holes in my bathroom. So I thought that before I buy a (relatively) expensive, ugly plastic hook, I will try to print one first.

The hooks

For the two vertical holes next to a sink, I used a Towel hook model by VetterFl. It's a design that I always wanted to try out: instead of an original hook, you have a crevice that securely holds any towel.

The original model had only a single mounting point. This design wouldn't cover the second hole of mine, and won't be as stable as well. Thus I increased the size of the model, and added the second hole, or more precisely: a slot. While there was enough space for a second hole, inserting a screw was a challenge. In my solution, the screw has to be inserted sideways and then rotated into the correct position. I also had to use a narrow screwdriver as it had to fit in the crevice.

Then I modeled a hook for the two horizontal holes next to a bathtub. As it was my design, I decided to take it up a notch and create a double hook. This involved plenty of OpenScad magic, including a Minkowski sum. It won't ever repeat it in the future, and I don't wish such a trial to anyone, now that I know about Fusion360.

After some time, my mother in law visited us. And she didn't have where to put her towel near the sink. So I unscrewed the fancy "hook" from the vertical holes and remixed my double hook to adopt vertical mounting points. After one day there was a new hook that could hold both our towel and the towel of my mother.

Bonus story

There were also two holes above a toilet situated horizontally about 25 centimeters apart. I have no clue about their function in the past, but I was often thinking about what can I install there. One day I stumbled upon a modular Toilet paper hexagon rack by atoomnet. I find it not only useful (remember, it's right next to a toilet), but it's also visually pleasing.

Epilog

Once you get a 3D printer, things are never going to be the same. I printed my own towel hooks for the exact needs that I had. And when the needs changed — I immediately adapted. And as we speak about changing needs… maybe I should update to a triple hook next to a bathtub because now the double hook is continuously occupied by the towels of our kids 🧒👶

Occasionally I design 3D models. Usually, I need to fix or improve something around the house. But sometimes I stumble upon a beautiful design, and I have some ideas on how to improve it. This is how last year I uploaded yet another model to the PrusaPrinters website: Screw-top Containers (Prusament Spool Reuse Idea).

My submission was a remix of a project: CONTAINERS - PRUSAMENT SPOOL - reuse idea. Its author — Dominik Císař created a few projects that demonstrated possible reuse of Prusament Spools. Prusament is a 3D printing filament by Prusa Research that comes on a spool with plastic sides and a center core made out of cardboard. These center cores can be reused as containers when closed from both sides. Dominik designed caps that would plug into the cardboard cylinder, and I had some other ideas. I like sturdy constructs, so I remixed the original models to have a fixed insert with a thread and a removable screw-cap.

This was one of the projects that I quickly hacked together and forgot about it. But then, after some time, my remix became a featured model on PrusaPrinters, and a bit later, it even appeared on Prusa weekly prints.

It's a fantastic feeling to see that your work gets such attention and recognition. However, there was one this which was bothering me: the threads on my models had a low resolution. And not only it looked ugly, but it also performed poorly. Seriously, look at the video from the 0:42 timestamp: the person in the video struggles to screw on the lid. As I mentioned before, this was a fast hack, so I didn't care about the details. But when it's featured, and people look at it, and print it, and use it — that's an entirely different story.

Fixing the Resolution

I did my remix in OpenScad, and this was not the first design of mine that required threads. For all of my previous models, I used the single threads library that appears on top of my Google search. This library, though, does not have a way to define the resolution. When you model something round in a 3D design app, it's composed of many flat sections. The higher the resolutions, the more sections, and the rounder your design appears to be. As you can see in the screenshot below: the thread is way more chunky than the rest of the design, especially the inclined surface right about the thread.

Usually, to define the resolution in OpenScad, you can assign values to variables like $fn either globally or by passing it to a function (or a module in OpenScad terminology). As nothing like this worked for me, I had to dig into the code of the threads library. And after a short time I found this definition of the number of segments based on a thread diameter:

In human language: the number of segments used to draw a circle (cylinder, cone, etc…) is equal to the diameter of this circle (in millimeters) multiplied by 6; not lower than 25; not higher than 50. It's a small range if you ask me. It only changes for diameters from approximately 4 to 8 millimeters, the rest result either in 25 segments or in 50 segments. This means that my ugly thread, which is close to 95mm in diameter, has the same number of segments as a 10mm thread.

The problem has a simple solution: change the upper limit directly in the library's code 😎. You can see how the rendered thread changes based on the number of the segment's that it had.

Ultimately, I increased the number of segments to 360 and printed a super-smooth model. It worked better. But it didn't work as smoothly as a jar of a raspberry jam, for example. Also, we adults are excellent in getting along with various imperfections, but with my daughter, it was clear that she struggled to align and close the lid that I printed.

Pst… are you also curious about what is that decorated pink container all about? Stay tuned for another post from my wife about how she created the container with our daughter as a part of a dealing-with-boredom-during-the-quarantine activity.

Jars not Bolts

The threads library that I was using in OpenScad is generating ISO metric threads. It has some comforting flexibility, but its primary focus is to generate threads according to a standard. This standard describes threads that are mainly used for nuts and bolts, and while this is desired for some prints, it does not work well with jars. And by jars, I mean all the jars. Take a look at a jam jar: it has a thread with four starts (i.e., four separate threads that coil in "parallel" to each other); each thread bearly does a quarter of a turn; there are four small grips on the metal lid; the lid stops at the beginning of the threads because the lid presses against the glass opening of the jar.

If you look at a plastic jar of cosmetic cream, it's different, but there are similar vital features. There are two starts on the threading; each separate thread makes at most one revolution; the threads are not "sharp" and have a looser spacing that the ones of nuts and bolts.

I decided to base my design on the jam jar, but make proper threads on the lid (I don't press the lid out of metal after all 😜).

The New Design

The OpenScad threads library is not flexible enough to easily create the threads similar to those on the jam jar. I could search for another library, and I have a feeling I could find a suitable one. But I decided to redesign everything in Fusion360. I started to use Fusion360 only a few weeks ago, and now each design that I do is a new learning experience. Threads are one of the things that I still didn't touch in Fusion360, so this looked like a worthy challenge. Finally, there were some parts that I don't like in the original design Dominik Císař, so building everything from scratch looked reasonable.

I re-created the plastic spool inserts of Prusment in as much detail as I could. When I finished, the printed part almost entirely resembled the injection-molded original… from 2018. Because then I found another spool from 2019 and they have a slightly different design. So I decided that it's good enough and screw perfection. Right, we are speaking about screws 🧐.

Fusion360 has a thread feature with many predefined standard profiles. If you need to create a thread that has to match some standard — this feature is perfect. If you need to make something at least slightly custom, then the Fusion360 threads feature is even worse than it's counterpart from OpenScad. Do you need a thread with a 96.72mm diameter? Forget about it! Only 95mm and 100mm are supported.

I created the suitable treads with the coil feature. As I needed four starts, I created a single-coil and quadrupled it as a circular pattern. I highly recommend the Layer by Layer - Using Coils for Threads video by Adafruit Industries if you need basic skills to create custom threads in Fusion360. For a more general overview, there is also 3D printed threads - 3 ways to model them in Fusion 360 video by CNC Kitchen.

I made sure that there is a 0.6mm distance between threads and walls. Usually, I need to have 0.1mm of clearance if I need something to fit into a hole. I choose to have a 0.5mm extra gap on purpose: I need a lid that is easy to put on and close.

The old version of the screwtop container was printed in Prusament Galaxy Black and Lipstick Red. Now I have a second version that I completely recreated from scratch. I printed the second version from Prusament Vanilla White and Azure Blue. You can see by yourself side by side how threads differ between the two versions.

The new threads slide smoothly and don't have issues with alignment. Even my three years old daughter can open and close the container pretty quickly. I will call this a Raspberry Jam Jar standard. I love raspberry jam.

Because the design is available online, you can download and print your own Prusament Screw-Top Container Conversion Kit as well. Also, if you are 3D printing, consider checking out Prusament if you have not so far. I like the quality very much, and together with shipping costs, its price is on the lowest range of 3D printing filaments that you can buy in Switzerland. Of course, it can be different in your country, but still worth checking.

If you don't use Prusament 🤔… would you like to see a remix that fits on a packing tape core? A toilet paper core? Probably, nowadays, with the coronavirus, it's easier to get a spool of Prusament than a roll of toilet paper 🧻.

Take care, and enjoy some beauty shots:

The idea to install Blinds on the South-East (mainly South) side of our balcony emerged about a half year ago. Last autumn, we started to put our son to sleep on the balcony. The morning sun was very annoying because it was shining directly through the South-East window of our balcony.

To create some shade, we ordered TRETUR roller blinds from IKEA. The blinds arrived with a couple of weeks of delay as IKEA was relocating its warehouse. Then we went for a vacation to Ukraine, and afterward, it was Winter, and we didn't go out on our balcony.

Fast-forward to now, and we are returning home from a skiing vacation. The corona virus is all around: ski resorts are closing, shops are closing, I'm working from home. And the best thing: it's warm, it's sunny, and I can work from our balcony. On Monday morning, I proudly start working from the balcony. It's still chilly, so I'm wearing a light jacket, but in an hour it becomes warm enough to wear just a t-shirt. And then closer to 10 AM, the sun creeps out from behind the wall, and I can't see anything on my screen… Now is the prime time to install the blinds.

The Setup

On the South-East side of the balcony, there are three stationary windows (they don't open). It would make sense to install the curtains in front of them.

The TRETUR blinds should be mounted with screws either to a wall or to a ceiling. They have metal plates that you mount first, and then attach the blind box to the metal plates.

There were two main options of attaching the blinds: 1) drill the balcony above us; 2) drill the metal frame of the windows. As we are renting this apartment, I don't want to drill anything that I can't cover up quickly (especially metal). So I decided to hook the blinds onto the metal frames of the windows. And yes, I designed and 3D printed the hooks.

The Solution

I started with a simple prototype that was going around the window frame and gripping it from the underside.

Besides some dimensional inconsistencies, it was clear that this design won't work at all on the leftmost window. As you can see on the left side of the photo, there is one window with a frame of a different shape (it is possible to open it for cleaning purposes).

I decided to abandon the gripping part on the inside arm and make it shorter to fit on every section on the window frame. This way, I had to deal with only one design while not sacrificing much. This part of the model should mostly experience the downwards force that comes from the wight of the blind. Thus there is not much sense in bracing the inner arm from an upward force.

The second challenge was to attach a metal mounting plate of the blinds to my hook. The holes on the mounting plates were 3.7mm in diameter, so I had to use M3 screws. I decided to use wide washers with 13mm diameter to distribute the force over a larger area (mainly for the printed model). I also decided to use nyloc nuts, so if the screws loosen, they will not undo themselves easily. Finally, as the plastic hook rests against the window frame, I had to make sure that the screw heads recess completely into the plastic model.

You can notice on the pictures above: there are no visible washers on the side of the printed object. This is because the washers are embedded. I could make large holes on the screw cap side, where a washer would fit together with a screw head. However, I decided to remove as little material from the hook as possible to maintain its durability. That's why I created narrow slots, where one can insert the washers.

I even took one step further and sealed the slots from the top. I've inserted the washers during the printing process, and then the print was finished on top of them.

I printed the final version from a white (natural) Prusament ASA. The plastic hooks will be exposed to the sun plenty the time, and it's useful if they have a good heat and UV resistance. I also printed them with 4 perimeters to increase their strength.

Wrap up

The blinds attached to the frame snugly and securely. I tested a bit the hooks by leaning onto the metal plates, and there should be no issue with the weight of the curtains.

I noticed, though, that the blinds are in a relatively open place. Rain can reach them easily, and they are completely open from behind. Now I'm working on a rain shield. It attaches into the mounting grooves on top of a blind and extends over the window frame. But this is a work in progress.

These blinds don't have some rope or stick to lower them — they have a small loop. IKEA sells a dedicated stick to reach the loop, but I just designed and printed the longest model I could fit on my print bed.

And this is it. I have blinds on my balcony. I can work there comfortably. Next week it will be cold and rainy, but what can you do? C'est la vie.

I try to publish a new post on this blog every Friday. This week, however, I'm on a Skiing vacation, and I have almost no time to do anything not related to the vacation. I already decided not to publish anything this week, but then something interesting happened to me. It's a short story, and it's worth sharing.

There is an outstanding 3D-printable design of a carabiner on Thingiverse: Origami Carabiner by ddf3d.com. At some point, I printed a bunch of them partially because I considered them to be useful, partially as benchmarks for new filaments. Usually, I have one attached to my backpack. It's useful to hook up a bottle of water or a bag of groceries to your backpack. Additionally, it's something that you can always show to other people when you tell them about 3D printing. And finally, it's a distinctive mark that other 3D printing enthusiasts can recognize.

I have one of these carabiners on my outdoor backpack that I'm using here. We were taking a gondola to the slopes, and I decided to change my jacket with the one that was in my backpack. As the floor of the gondola was wet and dirty, I didn't want to put my backpack down. There were no other surfaces where I could put my backpack. Usually, this would end up in silly acrobatics where I'm continuously holding the backpack while switching hands and changing the jackets. But when I was holding the backpack at the level of my waist, I realized the I can use the carabiner to attach it to my pants (or belt). This was very handy — I could do everything that I needed with both of my hands, without putting the backpack down.

Sometimes 3D printing can be helpful without dedicated designs and overcomplicated use cases ;)

Nowadays, my friends would tell you that I already bought at least half of the things that you can find on AliExpress. But some years ago, I was just starting to shop that the Chinese online hyper store. I was cautious by ordering only super cheap products, and precisely tracking if they arrive. At that time, I bought a flyswatter for $1.14.

It was a simple swatter with a plastic mesh and a telescopic handle. I killed flies with it, and I was happy 🤠. But after a couple of months, the plastic mesh cracked. And it's ok because I used it for a couple of months and paid $1.14 (in Switzerland you would pay at least $10 for such a thing).

But I don't surrender just like that, because it's about plastic — I can print it. I measured the original mesh with calipers and designed a clone in OpenScad. I printed the new swatter mesh in PETG because it has good impact resistance.

The new mesh from PETG resisted about one or two impacts and then snapped worse than the original. After some time, I bought a flexible filament (Formfutura FlexiFil; shore hardness 45D) and used it to print yet another version of the flyswatter mesh. The filament is on the stiffer side of the flexible materials spectrum, so the swatter is still hitting flies well. At the same time, it resembles a rubber, so it does not crack.

Since then, I used the swatter for 2 years, I killed many flies, and the ingenious killing device still works. Now I wonder if polypropylene would be a better material for the 3D printed mesh. It's stiffer than the flexible material that I used. However, it's still flexible, does not crack, and does not deform easily. But I have many more things in my "To Print" list, and while the swatter works I'm not going to change it 😝

A few years ago, we inherited a clamp-mounted lamp from the previous tenant of an apartment where we moved in. It was a white IKEA KVART that we occasionally used as a bed-side lamp.

About a year ago, our daughter Sophia learned how to turn on the lamp. Then she would wake up in the middle of the night and turn it on. This would wake my wife up because the light was very bright. Additionally, the light was too bright for falling asleep. Thus we thought about having a possibility to dim the light.

IKEA KVART is powered by 220V alternating current (i.e., you plug it into a standard power socket). The lightbulb that came with the lamp was of a compact fluorescent type, and they don't dim well. Incandescent light bulbs dim well, but they are super inefficient. LEDs may dim all right, but they are still not perfect. Another big question was how to add a dimmer to an AC power cord. There are some sketchy products on Aliexpress, but nothing that would be easy to install and works well out of the box.

I decided to make a physical dimmer: something that blocks the light coming from the lamp and can be easily adjusted.

The Iris Door

When I think about something that blocks light and can be adjusted, the first thing that comes into my mind is the aperture in a camera. I previously saw the Iris Door Box project on Thingiverse that used the aperture-like mechanism to open and close a container.

I decided to reuse the iris door mechanism and remix the top of the container to attach the mechanism to the lamp. I created a conical shape that follows the lamp's curvature, and so does not slip off. To install the conic adapter, I designed it with an opening that would be ultimately held together with a short M3 nut and a bolt.

I had to upscale the iris door model because the lamp's opening is larger than the container design. This brought additional problems. The iris door parts were designed to be held together with screws, but when I scaled up the parts, no screws would snugly fit. I modeled a peg that resembles a screw and is glued in the holes designed for the screws. To reinforce the pegs (avoid inter-layer cracks), I've hollowed them out and inserted toothpicks in the holes.

To match the color of the lamp, I printed the dimming mechanism in white color. Black would block too much light — you can turn off the lamp entirely in such a case. Colorful dimmer would also change the color of the light, and this was not desirable. I printed everything from PC-ABS. I wasn't sure how hot could the light bulb become, and PC-ABS has a high melting temperature. This material is also pretty durable and should handle the stress of constant use. Probably, the main reason to use that filament was the fact that I just got it and wanted to try it out. 😜

I also used a 3D cube infill, and this results in a stylish pattern of triangles that emerges when the lamp backlights the dimmer.

An Extra Story

Not long ago, when our son was born, my wife needed a way to quickly turn on and off the lamp without searching for the button and fiddling with it. I measured wooden beams on the bed and the switch on the lamp, made a couple of prototypes, and Bam💥! It took less than 2 hours to have a holder that snaps into a wooden beam and holds the lamp switch. This way, the switch is always in the same place, and it's easy to press it with a single finger.

Epilog

We use the unique, beautiful, flowery, dimmable lamp for a year already. Usually, it's dim. We can make it brighter. We can use it to bring some light at night. We can use it to read books before sleep.

I didn't buy a dimmable lamp — I reused a simple lamp that I had. I didn't design my dimmer — I used an existing mechanism. I didn't design the connector from scratch — I remixed it from an existing container. Reuse it, print it, and prosper 🖖

Almost two years ago, our family was traveling back home from a seaside vacation. We were waiting for our flight in an ugly airport section and I bought my daughter a toy car to brighten up the mood. It was a small Bburago model, which is more of a detailed replica rather than a durable toy that you can give to a two-year-old child. Ironically, in a few minutes after we unboxed the car, my daughter dropped it. One wheel broke off, and since then, the car was for one year on a "to repair" shelf. For a few times, I tried to glue the wheel back in place with a CA glue and with a UV-cured resin. All my tries were complete failures. I surrendered and accepted the fact that I can't repair that wheel.

Recently I stumbled upon the car again. Of course, I remembered that I couldn't repair the wheel. But I also thought that I don't have to repair it. I can make a completely new wheel. I can 3D print it.

Making it

I had to disassemble the car a bit and remove the wheel axle. I removed the leftovers of the broken wheel, as well as the other wheel from the axel. I discovered that the other wheel was cracked as well. Thus I was going to print two new wheels. It's even better to have the same wheels on a single axle to avoid disbalance.

Then I measured the wheels and the axle, designed a simple model of a new car wheel, and printed four of them. Although I only needed a couple of wheels, I printed some extra because one of them may break, or a print may fail. Ultimately, now I have two more extra wheels in case the rest of the original wheels fail. I ended the top of the print with a silvery filament to give a disc-like shine to the wheels.

All in all, the printed wheel mostly resembled the original one. It had a bit thicker walls, to allow double perimeters of a 0.4mm nozzle. I also added reinforcing ribs between the inner and the outer walls, as I was afraid that the inter-layer adhesion would be too weak, and the inner shaft will snap off.

Epilog

3D printing doesn't stop here. I could make a more detailed model: add tire treads; add more details to the tire disks; use a nozzle with a smaller diameter. I could have a separate model for tires and print them with TPU for a rubbery feel with a better grip. I will do this for other projects.

It's all about having things that work. A toy car that worked only for a few minutes and lies for a year broken on a shelf is upsetting. But it takes less than 30 minutes to design a new wheel. It takes less than 30 minutes to print four new wheels. And it's done. The car is fixed. Now the kids that throw it around and break something else. But this is another story ;)

Although we never talked about it, this year is destined to become a "travel year" for our family. We recently bought a car; our youngest kid already has a few months; now, it's time to explore what's around us. On the first of January, we drove to a marvelous ice palace near Schwarzsee in Switzerland. While we were walking along the trails of the frozen palace, my wife slipped and fell on icy ground. She managed to minimize the fall damage but ultimately struck her finger joint. The pain didn't go away for a week. While there were no fractures, a doctor suggested to tape fingers together to reduce motion and aid in recovery.

Taping two fingers together didn't make any sense for us. A tape is soft, and it won't restrict the motion that much. Tape does not breathe, and the adhesive compound can irritate the skin. Sometimes it's necessary to remove the restricting cast and put it back (to wash hands, etc…), and with tape, it's cumbersome.

This is why we thought about printing something to support the fingers while a bandage will hold everything together.

Rapid prototyping

There is no way to model something comfortable from the first try, especially if it has to interface with the human body tightly. This is why I made a few preliminary measurements with my trusty calipers, designed a most trivial prototype, and kept trying, and adjusting until it was acceptable.

In total, I printed four prototypes, and the last one became the cast that my wife would use. In this blog post, I'm describing each prototyping step that I went through.

First, I designed a mostly flat plate with a small curved ridge to fit between the fingers. This could already provide some support when bandaged to the fingers, and I could check if the length is appropriate and if the finger curvature makes sense.

Afterward, we decided to have something which encloses fingers from both sides. I increased the width so that the cast would wrap around the fingers, and we can test the fit even better. I also increase the length a bit. The main outcome showed that the holes are too small for the fingers.

The third prototype had larger openings for fingers and curved outer walls to make it sleeker. In the previous prototype, we noticed that the separator between fingers is supper uncomfortable at the place closest to the palm. Hence, this version also had a cutout between fingers. The third prototype had a good fit and could be used as a cast for fingers.

In the last prototype, I optimized the remaining deficiencies of its predecessor. To improve ergonomics, the whole model (both the external profile and the channels for fingers) narrows down towards the finger ends. I increased the length and enlarged the cutout between the fingers. This is the last prototype which my wife used for several days until the pain went away.

Oh, and have you seen the layers? I printed the model at 0.3mm layer height (the DRAFT quality in PrusaSlicer). I did this because printing speed was the main factor — it's a prototype, after all. Also, as there were not many slopes on the Z-axis, the final 0.3mm prototype was utterly usable, and thick layers didn't cause any annoyance.

Epilog

Unlike other posts, here I'm not motivating you to do the same. In fact, I hope you never have to do something like this. Also, there is no reason to share the finger cast model with other people. Everyone has different anatomy, and my model will most likely never work for others.

But think about this: my wife injured a finger and needed some assistance with recovery. I made a good cast such that:

1. it fits my wife's fingers well;
2. it didn't take much time to make (≈3 hours in the evening);
3. I could make it entirely at home;
4. it relieved the pain and helped the finger to heal.

At home, we have a MUM5 kitchen machine by Bosch. It's a handy device, but like anything else, it has certain weaknesses. In particular, we had problems with the citrus juicer attachment. As you can see in the following photo, the juicer is attached on top of an "arm," and I am worried about the stress that the arm experiences when I press an orange onto the juicer.

Secondly, the plastic protector on the wall behind the kitchen machine ends on the level of the juicer. This means that while juicing, the splatters eventually land on the wall.

Fun fact about 3D printing is that if you search for something popular, you have a high chance of finding existing models created by other people. So, for example, you can search for MUM5 or MUM4 (the previous model) on Thingiverse. In my case, there were no models that could help me. That's why I designed my own solutions to my problems.

Arm Support

To compensate for the force applied from the top on the kitchen machine's arm, I decided to create a supporting object on which that arm can firmly rest. The support would lock into the slot underneath of the arm, where one usually would attach a mixing bowl. Luckily for me, there was already a model of a Bosch MUM5 fake bowl, which is essentially a flat puck that would lock in place of the original mixing bowl. Thus I remixed the bottom of the support from the existing part. Then I only had to do measurements and design the top of the supports where it interfaces with the machine's arm.

Finally, I connected the two parts with three slim pylons that should equally distribute the load. I printed my model in PC-ABS because it was the only white filament I had at the time, and also I needed the print to be sturdy and withstand heavy loads.

Nowadays I think that PLA should be sufficient. This part mainly has to withstand the vertical compression force, which is applied perpendicularly to the layers, and PLA is pretty good with that (most of filaments are). Also, the support part experiences twisting stress when it's turned in and out of its locking position in the mixing bowl slot. This force mainly stresses the inter-layer adhesion, and I don't think that PC-ABS sticks better to itself in comparison to PLA.

Splatter Shield

A solution to the splatter problem was simple: add another layer of protection. It was reasonably easy to do a curved shield that follows the walls of the citrus juicer container and mounts on top of it.

I printed the shield from PETG. It's a relatively thin and large part, and I expect that the flexibility of PET increases the print's time of life.

Epilog

I don't blame Bosch for the design of this kitchen machine. It's an excellent device. The citrus juicer should work pretty well if you use it occasionally and gently. However, I just wanted to protect myself from possible breakage. Secondly, the juicer shield is specific to my situation, because of where I use the kitchen machine and how my kitchen is designed.

What is important is that I could solve my problems with 3D printing. And now, the models that I did are available for free to everyone:

• MUM5 Citrus Juicer Support
• MUM5 Citrus Juicer Shield

For the last birthday of my daughter, I gifted her potted flowers 💐. As usual, it came in a basic plastic pot full of holes to drain water. Typically, you also have to buy a beautiful decorative pot that will keep the water from spilling and, well… look nice. Then you just put the original plastic pot inside the decorative one. If the size difference is quite big, it may look ugly. And make sure that the base pot can fit into the outer pot, or you will have to re-pot the plant, and this is yet another headache.

I didn't think about the decorative pot once I was buying the flowers, but I started to think about it once I was at home. Of course, I thought about printing a pot as I already printed drip trays for pots of basil and other herbs in the past.

Modeling

For now, I design all my creations in OpenSCAD. I like the aspect of coding your model. As you model by coding, you can version your models with git and share them on GitHub. Finally, it was just easier to get started by uniting and intersecting cubes and spheres and not learning all the controls on full-fledged CAD software.

I started by measuring the plastic pot dimensions and implementing a reference object (it was as simple as two stacked conical cylinders).

Afterwards, I started to work with 2D side projections, or it's better to say crosssections. The pot is symmetrical around its central axis. Thus it's enough to create a 2D model and rotate it around its vertical center axis to obtain a final 3D pot. At the same time, it is easier to understand how the two objects will fit together when looking at their 2D crosssections.

I decided to go with a simple sphere-ish design that is elegant and easy to print (no overhangs). In the end, I finished the model by rotating the 2D crosssection around its center (notice that in OpenSCAD, you have to have all the 2D shapes on the positive side of the X-axis; thus, I removed the negative side before applying rotate extrude).

Printing

It's a pretty straightforward model to print. However, you throw in some nice improvement here. I set the position of the seam to be random to avoid a visible seam; I've set the top and bottom infills to archimedean chords (although almost no one will see them), but mainly I've added a color change. By printing the bottom part and the top ring in another color, I could improve the look of the pot even more. For this print, I used Prusament PLA Vanilla White and Lipstick Red.

Closing Ideas

This story is about a simple print that I made for my daughter to complement the flower bush that I gifted her. You can use the same idea when you plan to gift plants. Additionally, you can add embossed text to the printed pot, to make it even more personal. While many can buy a lovely plant 🌱, it's touching to know that someone designed and printed a pot especially for you 🤓

The watering can in the picture is the Small Watering Can by shmeeed. I printed it in PETG for my daughter to water her new plant.

You can check out the .scad file for the pot here: https://gist.github.com/Uko/61c499e8422eb2b17d954c656b8469d1