Designing A Fully 3D-Printed Mechanical Calculator

September 29, 2026 by Maya Posch 10 Comments

Even if almost tragically impractical in a world where digital calculators are cheap as chips, mechanical calculators and their big mechanical computer brethren remain an absolute marvel of engineering. Using nothing but elements like simple gears their motion is used to calculate everything from a simple multiplication to the proper targeting instructions for an Iowa-class battleship’s guns.

This fascination, along with the mind-bendingly high prices for commercial digital calculators led [3D all Workshop] to spend 2 months on designing his own mechanical calculator. Fully FDM 3D-printed, of course.

In the video the design process and troubleshooting step are covered along with the workings of the mechanisms for both addition and multiplication. While this may seem simple, basically converting numbers of rotations into a final indicator position, aspects like carrying a digit and adding a multiplication feature to the mechanism require some proper engineering.

Of course, using FDM printing for tolerance-sensitive things like gears meant that a lot of time was spent redesigning aspects of the mechanism, going through about a hundred design iterations until it worked, with the help from a bit of lubrication.

Naturally this isn’t the first 3D-printed mechanical calculator, not to mention ones made from wood, but always it’s pretty cool to see one made from first fundamentals.

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Forget Trees, Add Fins To Your 3D Prints Instead

September 23, 2026 by Maya Posch 23 Comments

Perhaps one of the most contentious issues in 3D printing is that of supports, both because they’re an uncomfortable reminder of how gravity affects our prints and because the very idea of there being ‘one right way’ is bound to get you into some spirited discussions. That said, [Matthew Trahan] figured that neither regular grid supports nor organic tree supports are the answer here, and that the better answer is found in fins.

The problem with existing support approaches especially with FDM prints is that they can be fairly wasteful in terms of material, and they can leave serious marks on the printed object’s surface that require post-processing. These fins on the other hand are designed to require as little material as possible and snap off as cleanly as possible. The tool, developed with the assistance of Claude, can either run locally or be accessed via printfins.com.

Currently the idea is that these fins are baked directly into the STL model so that it’s a one-time thing, but it may eventually become available as a slicer plugin. The basic concept was pitched by [Slant3D], who gets credited in the video below, although in their approach they used CAD software to add the fin supports manually.

The fins are there to provide the support base, while small tines can be added to reinforce the connection to the model. These do make it less easy to snap off with minimal scarring, of course. Conceivably these fins could be made even more light-weight by adding gaps, but that probably would add to the print time.

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Full-Color Looks Great On 3D Printed Sliding Puzzles

September 16, 2026 by Donald Papp 4 Comments

[Angus] of [Maker’s Muse] shows off both a parametric, print-in-place sliding puzzle design he created, and the results of UV printing full-color designs on the same. The results look beautiful, and there was a whole lot of trial and error involved in the process.

The design includes a pop-out tile, which can be re-inserted to a finished puzzle.

Creating a good print-in-place sliding puzzle depends a lot on tolerances. Today’s 3D printers are much more capable in this regard than they were ten or so years ago, but getting the right feel to the pieces was still a long learning process. It’s not at all easy to get all the different characteristics in the right balance. On one hand, if the pieces are too tight they won’t slide easily. But if they are too loose, the puzzle can bind because the pieces have too much play. It may also flex enough to pop apart. And of course, the shape of the pieces and their mating surfaces are constrained to angles and shapes that 3D print reliably. [Angus] persevered and succeeded, and shows off everything from cute 3 x 3 units to a massive scaled-up 11 x 11 puzzle, printed on his Prusa XL.

Getting the color onto the print is the work of a desktop UV ink printer, the same model our own Tom Nardi had a hands-on look at last year. [Angus] shows how printing a single color image onto the puzzle is pretty easy and looks great, but what’s even better is a textured relief image with some real tactile depth to it. Expect a lot more work to do for that, because thick layers of ink gum the puzzle up with overspray unless one avoids printing over the gaps in the tiles.

Watch both the puzzles and the color printing in action in his video, embedded just below.

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Changing Nozzle Internal Geometry To Increase FDM Flowrate

September 10, 2026 by Maya Posch 20 Comments

As FDM printers keep getting faster, we are forced to deal with a range of bottlenecks, all of which conspire to hold us back from another Benchie world record. A major physical limitation is that of flowrate, as the hotend has to be able to melt the filament that enters the nozzle before it departs said nozzle. One attempt to make a high-flow nozzle involves splitting the material path into three winding sections, which theoretically should help said flowrate. Recently [Thomas Sanladerer] took a poke at this and other types of nozzle with SLS-printed nozzles.

These printed parts still needed some finishing on the lathe, including drilling the 0.4 mm nozzle hole. The finished nozzles feature a variety of internal geometries, including the aforementioned triple-path, as well as many with various intrusions that seek to maximize the contact area.

Using a Prusa Core One these nozzles were subsequently tested to see what print quality they produced at high flow rates. A special test rig to test the nozzle pressure was also used to further characterize them, as this indicates at which flowrate the nozzle begins to struggle. Among these the Fuge design did the best, though with the big asterisk that these nozzles were printed in MS1, which is in effect tool steel and thus not great for being nozzles.

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Creating A Custom Hinge For A Motorbike’s Fuel Access Panel

September 10, 2026 by Maya Posch 6 Comments

A fun part of modifying something like a motorbike is that you sometimes have to come up with creative solutions to basic questions, like how you can still access the fuel tank’s cap after extending it forward. In the case of [KRTframework] this meant that the fuel cap was now underneath the bodywork, requiring a suitable way to access it. Of course, this meant making a hidden access panel with a custom hinge, to not break the bike’s clean lines.

To make the process as easy as possible, a 3D scanner was used to get detailed measurements on what the new bodywork would look like. Using these the new bodywork was created, including what would be the hidden access panel, yet finding a suitable hinge mechanism wasn’t easy. This is where this custom design was created, with detailed assembly covered in the video.

To bridge the gap between the opening and the fuel tank a part was 3D-printed that also contains the simple push-to-open latch mechanism. Of course, in the comment section people sounded off on this, feeling that it would be far too easy to accidentally open the panel.

The hinge seems to be well-received at least, with it having to fit within the available space, while also providing good access to the fuel cap when opened, meaning quite a lot of travel.

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3D Printable Lenticular Indicators

September 9, 2026 by Zoe Skyforest 19 Comments

You can 3D print all kinds of things, from Yoda heads to little models of Pikachu. Eventually, though, most of us get to a point where we want to print something a little more interesting. The lenticular prints developed by MIT CSAIL are very much that. (h/t Core77).

The ShiftLens concept is simple enough—there’s a lens layer printed in transparent material. Beneath that, lives a patterned layer in alternating colors, corresponding with the linear lenses of the layer above. Then, there’s an actuation mechanism that can shift the lens layer relative to the pattern layer. This creates a changing color effect as the mechanism is shifted. The actuation mechanism can be a knob, switch, or roller—anything that moves the layers relative to each other. On its own, it’s a bit of a curio—but there are some fun demos. In particular, using the lenticular printing on a bottle to form an indicator for when the container is closed properly. There isn’t a publicly available design tool for these prints yet, though the team developed one for Rhino that they used internally for the project.

It’s a pretty interesting application of 3D printing, and one that we fully expect a bunch of YouTubers to replicate within the month. We’ve featured some other great print hacks lately, too, like a slicer that lets you print horizontal overhangs without support. Video after the break.

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Are Desktop PC-ABS Prints Outperformed By Industrial FDM? Not Really

September 8, 2026 by Donald Papp 18 Comments

[Igor] of [My Tech Fun] set out to discover what differences, if any, can be found between parts printed in PC-ABS filament on an industrial 3D printer, and those from prosumer-grade machines and filament. His video is full of his usual attention to detail as he compares a test suite of parts printed at home in Polymaker PC-ABS with those from a Stratasys Fortus 450mc using proprietary PC-ABS filament.

PC-ABS is a filament that strives to deliver the benefits of both polycarbonate and ABS. It’s durable and has fantastic impact resistance, but it costs a bit more than either PC or ABS and requires a heated chamber.

[Igor] has previously compared industrial ABS with comsumer ABS, but what made him curious about PC-ABS in particular was the large difference in print temperatures between Polymaker PC-ABS, and Stratasys’s own proprietary PC-ABS.

[Igor] prints Polymaker filament at 280º C in a 60-65º C chamber, whereas the Stratasys filament prints at 325º C with a chamber temperature of 95º C. That’s quite a difference. The industrial printer has over double the print time, to boot. Would test objects printed from the industrial filament, on an industrial machine, be noticeably different from those printed at home?

To find out, [Igor] orders a test suite of parts from a company with a Stratasys Fortus 450mc (who was also kind enough to take a short video of the machine in action) and prints his own on both a Prusa Core One L, and a Bambu Labs H2D. He then proceeds to compare them in a variety of ways while testing them to destruction.

What’s the bottom line? The industrial prints have better dimensional accuracy, but the home prints have the edge in appearance. When it comes to performance the differences are mostly minor, and not always in the industrial system’s favor. Broadly speaking, PC-ABS from the home workshop compares very favorably from an expensive industrial system and proprietary filament, at a fraction of the price. See it for yourself in the video, embedded just below.

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