3D Printed Train Whistles Sound Out At Full Scale

May 7, 2026 by Tyler August 10 Comments

The age of steam is long gone, but there are few railfans who don’t have a soft spot for the old rolling kettles. So you’d best believe when [AeroKoi] talks about 3D printed train whistles, that’s steam whistles. Generally speaking, Diesels have horns.

You would not expect printed plastic to hold up to live steam– but that’s why [AeroKoi] uses compressed air. Besides, it’s a lot easier to both justify and maintain an air compressor than a boiler in the shop. At least some hobbyists say it doesn’t make a huge difference with brass whistles, so it should be good enough for plastic. What’s interesting is that even with 120 PSI blasting through them, these multi-part prints held together and sounded amazing.

[AeroKoi] does demonstrate there was a learning curve to climb before he had a good whistle design, and shows you what features worked best. He shared two successes on Thingiverse: A 6-Chime whistle from the Sante Fe Railroad, and a Northern Pacific 5-chime whistle, both 4″ in diameter and printed in vertically sectioned parts. The Northern Pacific is not to be confused with the totally different Union Pacific Railroad, whose famous “Big Boy” also had a whistle feature in the video — though evidently he’s not as happy with it, since he did not share the design.

Those are all North American designs, but there’s no reason this technique wouldn’t work to replicate a more European sound; one of his early experiments was kind of going in that direction already. Of course if you want a perfect replica, the old ways are the best ways: cast brass and live steam. We’ve had a few articles about train whistles in the past, one of which was a doorbell.

Continue reading “3D Printed Train Whistles Sound Out At Full Scale” →

Direct FDM Printing With Granules

May 6, 2026 by Maya Posch 16 Comments

The idea of FDM 3D printing using granules rather than filament is an appealing one: rather than having to wrangle spools of filament that need to adhere to strict dimensions and cannot be too flexible, you can instead just keep topping up a big hopper with fresh granules. This is what [HomoFaciens] has been tinkering with for a while now, with their Direct Granules Extruder V7.0 showing significant improvements.

There’s also an accompanying article, with details of previous granule extruder attempts detailed on the same site. Many of the improvements here focus on making sure the granules melt properly before they reach the end of the extruder, with the auger screw helping to push things along. While this seems straightforward, there are many details to get right, with the previous v6.2 version having issues like the hot plastic backing up into the cold section and clogging things up.

For the test bench a Prusa Mk4 FDM printer is used, with the standard extruder swapped for the experimental extruder. On the extruder the cold, top part is water cooled to ensure it stays cold, with each turn of the wood-screw-turned-auger providing the right extrusion speed. As can be seen with the print tests, the results look pretty good despite the extruder not having been tuned yet.

If you want to give it a shot yourself, the article page provides files for download.

Continue reading “Direct FDM Printing With Granules” →

3D Printed Orrery Runs On A Single Motor

May 1, 2026 by Zoe Skyforest 17 Comments

The solar system is kind of hard to observe in motion all at once. Sometimes, it’s nice to have a little model to look at, so you can see the relative motions of celestial bodies play out in front of you. Such a device is called an orrery, and [illusionmanager] has built rather a nice example of their own.

The build represents all the planets in the solar system, plus the sun and our very own Moon. An ESP32 lives at the heart of the build, running an astronomical simulation to calculate the proper positions of all the celestial objects. It then drives a small stepper motor via a TMC2209 driver, turning the mechanism back and forth until all the pieces are positioned correctly, using a reed switch and magnet to detect the initial zero position. The orrery is able to be driven by a single motor in this manner thanks to an ingenious mechanism, wherein the rings interlock with each other using small tabs. The Moon is controlled by a separate geared mechanism connected to the main rotation.

It’ s a nice decoration that also serves as a great conversation piece, particularly if you like talking about the heavens. We’ve featured some fine works from [illusionmanager] before, too, like this exquisite reverse sundial. Video after the break.

Continue reading “3D Printed Orrery Runs On A Single Motor” →

Recycling PLA And Other Plastic Waste With Compression Molding

April 28, 2026 by Maya Posch 4 Comments

After previously trying out low-tech compression molding with a toaster oven and 3D printed molds, [future things] is back with a video that seeks to explore some of the questions raised after the first video. Questions such as how well this method works with HDPE and PLA thermoplastics, whether the flashing could be cut off by the mold and the right temperatures and times to heat the plastic before a charge is ready for inserting into the mold.

In this video the same PHA-based mold is used, but in a three-piece configuration to allow for a more complex shape. This way game tokens could be made for use by the son of the author, which also shows one straightforward and very practical use of this method.

A big change here is that no more metal chopsticks are used to handle the charge, as this was found to cool down the heated plastic too much. Instead the hot charge is handled with fingers and wooden chopsticks, with the plastic heated until it has about the consistency of thick honey. For LDPE this takes about 5-7 minutes at 130°C. After compressing the charge into the mold, about 30 seconds are all it takes for the plastic to cool down enough.

There was a question about the use of mold release spray, but this didn’t seem to cause any issues, so can probably be used safely. As for other plastic types, HDPE works fine too when you heat it up at a slightly higher temperature and don’t mind it being tougher to handle.

Easiest is probably PLA, which would seem unsurprising. Using some chopped-up PLA printing waste it was easy enough to make a few more game tokens, demonstrating that this method is very viable for converting scrap FDM print waste into such items. As noted in the comments by [edmundchao] this method works great too for PETG, using PETG molds, while using a ratcheting clamp for extra pressure instead of just pressing by hand.

Continue reading “Recycling PLA And Other Plastic Waste With Compression Molding” →

Can You 3D Print A Pinball Machine That’s Fun To Play?

April 28, 2026 by Maya Posch 8 Comments

It seems fair to say that pinball machines are among the most universally loved gaming systems known today, yet the full-sized ones are both very expensive and very large, while even the good quality table-sized ones tend to be on the expensive side. That raises the question of whether a fully 3D printed pinball machine could at all be fun and not just feel like a cheapo toy? A recent video by [Steven] from [3D Printer Academy] on YouTube makes here a compelling argument that it might actually be worth something to consider.

In addition to being fully modular and customizable the most compelling element is probably that the design supports two- and four-player multiplayer. This sees the metal balls leaving at the rear and from there entering the playing field of another player’s machine, which can probably get pretty chaotic.

Unfortunately this is part of a Kickstarter campaign, so you’ll have to either shell out some cash to get access to the print files or DIY your own version. We’d also be remiss to not address the durability concerns of a 100% plastic pinball machine like this, plus the lack of serious heft to compensate for more enthusiastic playing styles.

If you are more into traditional DIY pinball machines, we have covered these as well, along with small screen-based machines, and their miniature brethren for when space is really at a premium.

Continue reading “Can You 3D Print A Pinball Machine That’s Fun To Play?” →

New Slicer Enables Horizontal Overhangs Without Support

April 28, 2026 by Zoe Skyforest 16 Comments

There’s a rule of thumb when it comes to FDM printing that overhangs are really only possible to an angle of around 45 degrees or so. If you try to squirt out plastic with nothing supporting it, it just goes everywhere. However, a new slicer hopes to enable printing up to 90-degree overhangs with some creative techniques.

The software that enables this is called WaveOverhangs, and currently exists as a fork of OrcaSlicer. The idea is straightforward enough — using unique toolpathing to create rings of deposited material that fasten to those laid down before them in the same layer. Thus as the printer lays down a layer into bare space, the deposited plastic is, ideally, able to fix on to the supported edge. As the next ring is laid down, it grabs on to the cooled ring laid down before it, and so on. The idea is inspired by wave propagation, hence the name. You can see a demonstration of the software in the video below by [Cocoanix 3D Printing].

It’s still a very new technique. The slicer has a whole bunch of knobs to turn and two different algorithms. Get the settings just right and you can print horizontal overhangs successfully. There aren’t exactly presets yet, this is something to explore with trial and error. If you test it out, don’t forget to upload your results to the Community Gallery so the developers can see what works and what doesn’t.

We’ve explored how smart slicers can do amazing things before, too, particularly when it comes to things like bridging.

Continue reading “New Slicer Enables Horizontal Overhangs Without Support” →

The Challenges Of 3D Printing Reliable Springs

April 27, 2026 by Maya Posch 19 Comments

Springs are great, but making them out of plastic tends to come with some downsides, for fairly obvious reasons. Creating a compliant mechanism that can be 3D printed and yet which doesn’t permanently deform or wear out after a few uses is therefore a bit of a struggle. The compliant toggle mechanism that [neotoy] designed is said to have addressed those issues, with the model available on Printables for anyone to give a shake.

The model in question is a toggle, which is the commonly seen plastic or metal device that clamps down on e.g. rope or cord and requires you to push on it to have it release said clamping force. Normally these use a metal spring inside, but this version is fully 3D printable and thus forms a practical way to test this particular compliant mechanism with a variety of materials.

The internal spring is a printed spiral spring, with the example in the video printed in PETG. You can of course also print it in other materials for different durability and springiness properties. As noted in the video, PLA makes for a very poor spring material, so you probably want to skip that one.

We covered compliant mechanisms in the past for purposes like blasters, including some that you can only see under a microscope.

Continue reading “The Challenges Of 3D Printing Reliable Springs” →