multimaterial

14 Articles

Multi-material Parts The Easy Way

January 10, 2026 by 14 Comments

You have a part that needs different colors or different material properties — with a multi-color 3D printer, no problem. You can also laboriously switch filaments on a single-color printer. But [anonymous kiwi] points out a different way, which is surprisingly obvious once you think about it. You simply add a previously made part to another one.

If you’ve ever experimented with adding a nut or a magnet into a print in the middle, the idea is exactly the same: you print one piece and then print a second piece, pausing in the middle to insert the completed first piece. The video example shows TPU robot wheels with PLA hubs. Of course, the same idea could apply to using different colors or even multiple materials or parts. You could imagine a hub with a steel nut embedded in it, then further being embedded in a TPU wheel, for example.

With multi-material printers becoming more commonplace, this technique might seem antiquated. But even if you have one of such a printer, this technique could save time and reduce waste. Not every part would work out this cleanly, but it is something to remember for the times when it does.

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SLM Co-extruding Hotend Makes Poopless Prints

October 13, 2025 by 17 Comments

Everyone loves colourful 3D prints, but nobody loves prime towers, “printer poop” and all the plastic waste associated with most multi-material setups. Over the years, there’s been no shortage of people trying to come up with a better way, and now it’s time for [Roetz] to toss his hat into the ring, with his patent-proof, open-source Roetz-End. You can see it work in the video below.

The Roetz-End is, as you might guess, a hot-end that [Roetz] designed to facilitate directional material printing. He utilizes SLM 3D printing of aluminum to create a four-in-one hotend, where four filaments are input and one filament is output. It’s co-extrusion, but in the hot-end and not the nozzle, as is more often seen. The stream coming out of the hot end is unmixed and has four distinct coloured sections. It’s like making bi-colour filament, but with two more colours, each aligned with one possible direction of travel of the nozzle.

What you get is ‘directional material deposition’: which colour ends up on the outer perimeter depends on how the nozzle is moving, just like with bi-color filaments– though far more reliably. That’s great for making cubes with distinctly-coloured sides, but there’s more to it than that. Printing at an angle can get neighboring filaments to mix; he demonstrates how well this mixing works by producing a gradient at (4:30). The colour gradients and combinations on more complicated prints are delightful.

Is it an MMU replacement? Not as-built. Perhaps with another axis– either turning the hot-end or the bed to control the direction of flow completely, so the colours could mix however you’d like, we could call it such. That’s discussed in the “patent” section of the video, but has not yet been implemented. This technique also isn’t going to replace MMU or multitool setups for people who want to print dissimilar materials for easily-removable supports, but co-extruding materials like PLA and TPU in this device creates the possibility for some interesting composites, as we’ve discussed before.

As for being “patent-proof” — [Roetz] believes that through publishing his work on YouTube and GitHub into the public domain, he has put this out as “prior art” which should block any entity from successfully filing a patent. It worked for Robert A. Heinlein with the waterbed, but that was a long time ago. Time will tell if this is a way to revive open hardware in 3D printing.

It’s certainly a neat idea, and we thank [CityZen] for the tip.

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