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.

Continue reading “SLM Co-extruding Hotend Makes Poopless Prints” →

[Anthony] holding the EE8 kit

Making A 2-Transistor AM Radio With A Philips Electronic Engineer EE8 Kit From 1966

October 12, 2025 by 31 Comments

Back in 1966, a suitable toy for a geeky kid was a radio kit. You could find simple crystal radio sets or some more advanced ones. But some lucky kids got the Philips Electronic Engineer EE8 Kit on Christmas morning. [Anthony Francis-Jones] shows us how to build a 2-transistor AM radio from a Philips Electronic Engineer EE8 Kit.

According to [The Radar Room], the kit wasn’t just an AM radio. It had multiple circuits to make (one at a time, of course), ranging from a code oscillator to a “wetness detector.”

The kit came with a breadboard and some overlays for the various circuits, along with the required components. It relied on springs, friction, and gravity to hold most of the components to the breadboard. A little wire is used, but mostly the components are connected to each other with their leads and spring terminals.

Continue reading “Making A 2-Transistor AM Radio With A Philips Electronic Engineer EE8 Kit From 1966” →

The Singing Dentures Of Manchester And Other Places

October 12, 2025 by 38 Comments

Any radio amateur will tell you about the spectre of TVI, of their transmissions being inadvertently demodulated by the smallest of non-linearity in the neighbouring antenna systems, and spewing forth from the speakers of all and sundry. It’s very much a thing that the most unlikely of circuits can function as radio receivers, but… teeth? [Ringway Manchester] investigates tales of musical dental work.

Going through a series of news reports over the decades, including one of Lucille Ball uncovering a hidden Japanese spy transmitter, it’s something all experts who have looked at the issue have concluded there is little evidence for. It was also investigated by Mythbusters. But it’s an alluring tale, so is it entirely fabricated? What we can say is that teeth are sensitive to sound, not in themselves, but because the jaw provides a good path bringing vibrations to the region of the ear. And it’s certainly possible that the active chemical environment surrounding a metal filling in a patient’s mouth could give rise to electrical non-linearities. But could a human body in an ordinary RF environment act as a good enough antenna to provide enough energy for something to happen? We have our doubts.

It’s a perennial story (even in fiction), though, and we’re guessing that proof will come over the coming decades. If the tales of dental music and DJs continue after AM (or Long Wave in Europe) transmissions have been turned off, then it’s likely they’re more in the mind than in the mouth. If not, then we might have missed a radio phenomenon. The video is below the break.

Continue reading “The Singing Dentures Of Manchester And Other Places” →

Hackaday Links Column Banner

Hackaday Links: October 12, 2025

October 12, 2025 by 1 Comment

We’ve probably all seen some old newsreel or documentary from The Before Times where the narrator, using his best Mid-Atlantic accent, described those newfangled computers as “thinking machines,” or better yet, “electronic brains.” It was an apt description, at least considering that the intended audience had no other frame of reference at a time when the most complex machine they were familiar with was a telephone. But what if the whole “brain” thing could be taken more literally? We’ll have to figure that out soon if these computers powered by miniature human brains end up getting any traction.

Continue reading “Hackaday Links: October 12, 2025” →

DIY 35mm Film Scanning

October 12, 2025 by 24 Comments

If you are sitting on a horde of negatives, waiting for the digital photography fad to die off, it may be time to think about digitizing your old film. [Kinpro1024] can help with the PiDigitzier, an open-source film scanning solution. The build centers around a Pi Zero 2, a Pi HQ camera, and a diffusing  LED lighting fixture. Of course, there’s also some miscellaneous hardware and a camera lens; the example used a Pentax 50 mm f1.8 lens.

Half of the project is mechanical. An MDF tower provides a stable 250 mm workspace and decks that can slide up and down using threaded rods and curtain rods. Apparently, leveling the platforms is important not only for the optics but also to allow the MDF to move along the rods without binding.

Continue reading “DIY 35mm Film Scanning” →

PVC Pipe Structure Design That Skips Additional Hardware

October 12, 2025 by 46 Comments

[Baptiste Marx] shares his take on designing emergency structures using PVC pipe in a way that requires an absolute minimum of added parts. CINTRE (French, English coverage article here) is his collection of joint designs, with examples of how they can be worked into a variety of structures.

Basic joints have many different applications.

PVC pipe is inexpensive, widely available, and can often be salvaged in useful quantities even in disaster areas because of its wide use in plumbing and as conduits in construction. It can be cut with simple tools, and once softened with heat, it can be re-formed easily.

What is really clever about [Baptiste]’s designs is that there is little need for external fasteners or hardware. Cable ties are all that’s required to provide the structural element of many things. Two sawhorse-like assemblies, combined with a flat surface, make up a table, for example.

Continue reading “PVC Pipe Structure Design That Skips Additional Hardware” →

Tubeless X-Ray Runs On Patience

October 12, 2025 by 6 Comments

Every time we check in on [Project326], he’s doing something different with X-rays. This week, he has a passive X-ray imager. On paper, it looks great. No special tube is required and no high voltage needed. Actually, no voltage is needed at all. Of course, there’s no free lunch. What it does take is a long time to produce an image.

While working on the “easy peasy X-ray machine,” dental X-ray film worked well for imaging with a weak X-ray source. He found that the film would also detect exposure to americium 241. So technically, not an X-ray in the strictest sense, but a radioactive image that uses gamma rays to expose the film. But to normal people, a picture of the inside of something is an X-ray even when it isn’t.

Continue reading “Tubeless X-Ray Runs On Patience” →