3D Printed Mail Is A Modern Solution To An Ancient Problem

November 13, 2025 by Tyler August 25 Comments

The human body and sharp objects don’t get along very well, especially when they are being wielded with ill-intent. Since antiquity there have been various forms of armor designed to protect the wearer, but thankfully these days random sword fights don’t often break out on the street. Still, [SCREEN TESTED] wanted to test the viability of 3D printed chain mail — if not for actual combat, at least for re-enactment purposes.

He uses tough PLA to crank out a bed worth of what looks like [ZeroAlligator]’s PipeLink Chainmail Fabric, which just so happens to be the trending result on Bambu’s MakerWorld currently. The video shows several types of mail on the printer, but the test dummy only gets the one H-type pattern, which is a pity — there’s a whole realm of tests waiting to be done on different mail patterns and filament types.

In any case, the mail holds up fairly well to puncture from scissors and screwdrivers — with a heavy sweater or proper gambeson (a quilted cloth underlayer commonly worn with armor) on underneath, it looks like it could actually protect you. To slashing blows, PLA holds up astoundingly well, barely marked even by slashes from an actual sword. As for projectiles, well, everyone knows that to an arrow, chain mail is made of holes, and this PLA-based armor is no different (as you can see at 8:30 in the video below).

If you want to be really safe when the world goes Mad Max, you’d probably want actual chain mail, perhaps from stainless steel. On the other hand, if someone tries to mug you on the way home from a con, cosplay armor might actually keep you safer than one might first suspect. It’s not great armor, but it’s a great result for homemade plastic armor.

Of course you’d still be better off with Stepahnie Kwolek’s great invention, Kevlar.

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There’s No Rust On This Ironclad Kernel

November 12, 2025 by Tyler August 18 Comments

Rust is the new hotness in programming languages because of how solid its memory protections are. Race conditions and memory leaks are hardly new issues however, and as greybeards are wont to point out, they were kind of a solved problem already: we have Ada. So if you want a memory-protected kernel but aren’t interested in the new kids’ rusty code, you might be interested in the Ironclad OS kernel, written entirely in Ada.

OK, not entirely in classic Ada– they claim to use SPARK, too, but since SPARK and Ada converged syntax-wise over a decade ago, we’re just going to call it Ada. The SPARK toolchain means they can get this kernel “formally-verified” however, which is a big selling point. If you’re not into CS, that just means the compiler can confirm the code is going to do what we want under all possible conditions — which is a nice thing to be able to say about the heart of your operating system, I think we can all agree. It’s a nice thing to be able to say about any code, which is one reason why you might want to be programming in Ada.

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Switch Switch 2 To CRT

November 10, 2025 by Tyler August 9 Comments

Have you ever imagined what the Nintendo Switch would look like if Nintendo had produced it in the mid-1990s? [Joel Creates] evidently did, because that’s exactly what this retro CRT-toting Switch 2 dock looks like.

Yes, it is portable, thanks to a 100W power bank torn apart and built into the 3D printed case. The full-color CRT comes from a portable TV, so it’s got portability in its heritage. Fitting all that chunky CRT goodness into a hand-held was, of course, a challenge. [Joel] credits AI slop with inspiring the 45-degree angle he eventually settled on. However, the idea of recessing handles inside the case so it could be thick enough but still comfortable to hold was all base-model H.Sap brainpower. There are shoulder controls hidden in those recesses, too, for the games that can use them.

We particularly like the cartridge-like way the Switch 2 slides into place with a satisfying click as its USB-C port connects. It’s plugging into an extension cable that leads to the guts of an official Nintendo dock, buried deeply (and conveniently) inside the 3D-printed box, stacked neatly with the HDMI-to-VGA and VGA-to-Composite converters [Joel] needed to get a nice 4:3 image on the CRT. No word on if he blows on the Switch 2 before plugging it in, but we certainly would.

We’ve featured plenty of portable game systems over the years, and some have been very well done, like this exquisitely done PS2 conversion — but very few have brought CRTs to the party. This retrofitted Game Boy is about the only exception, and [Joel] calls it out in his video as inspiration.

It looks like this is the first Switch 2 hack we’ve featured (with the exception of a teardown or two), so if you know of more, please let us know.

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Target The Best AA, And Take No Flak

November 9, 2025 by Tyler August 68 Comments

In this era of cheap lithium pouch cells, it might seem mildly anachronistic to build AA batteries into a project. There are enough valid reasons to do so, however, and enough legacy hardware that still takes AAs, that it’s worth spending some time deciding which batteries to use. Luckily for us, [Lumencraft] over on YouTube has done the legwork in the video embedded below, and even produced a handy-dandy spreadsheet.

Each battery in the test underwent three separate tests. There was the “leave it in a flashlight ’til it dies” test for real-world usage, but also discharge curves logged at 250mA and 2A. The curves for each are embedded in the spreadsheet so you can see what to expect, along with the calculated capacity at each discharge rate. 2A seems like a fairly brutal load for AAs, but it’s great to see how these cells react to extremes. The spreadsheet also includes the cell’s cost to create a value ranking, which will be of great use to our readers in the USA, where it appears [Lumencraft] is buying batteries. The world market is likely to have the same batteries available, but prices may vary by region, so it’s worth double-checking.

In the video, [Lumencraft] also takes the time to explain the four battery types commonly found in AA format, and the strengths and weaknesses of each chemistry that might cause you to prefer one over another for specific use cases, rather than going by his value rankings. Unsurprisingly, there’s virtually no reason other than cost to go for alkaline batteries in 2025. However, lithium-ion batteries in AA form don’t really outperform NiMH enough to make the added cost worthwhile in all applications, which is why the overall “best battery” is a “PowerOwl” NiMH. Li-ion’s unspectacular performance is likely in part due to the inefficiencies introduced by a built-in buck converter and safety circuitry. On the other hand, some people might really appreciate that extra safety compared to bare 18650 cells.

The results here aren’t too dissimilar to what we saw earlier this year, but we really appreciate [Lumencraft] publishing his results as a spreadsheet for easy reference. The only caveat is that he’s taking manufacturers at their word as to how many cycles the batteries will last.

Oh, and just to be 100% clear — we are talking about double-A batteries, not Anti-Aircraft batteries. If anyone has an anti-aircraft battery hack (especially if that hack includes double-A batteries powering the AA batteries), please send in a tip.

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Screen-Accurate Lightsaber As A Practical Effect

November 7, 2025 by Tyler August 18 Comments

The lightsaber was one of the coolest and most iconic visual effects from the original Star Wars, and people have been trying to get that particular piece of movie magic off the silver screen for about 40 years now. [HeroTech] seems to have cracked the code with their “Impossible Lightsaber”— it’s fully retractable, fully lit, and able to hit things (lightly), all while fitting into a replica prop handle.

The secret is… well, there’s more than one secret, here. The blade itself is made out of a “magician’s cane”, which is a coil of plastic that can spring outwards on demand for magic tricks. Hidden inside of it is a strip of LED lights. Of course one strip of LEDs would not be omnidirectional, and the magician’s cane is pretty floppy, but both of those problems are solved by the same idea: “I’ll try spinning. That’s a good trick.”

The spin-stabilized blade holds up to being waved around much better, and apparently the gyroscopic forces it induces are actually lore-accurate. (Who knew?) Of course fitting a motor to spin the “blade”, and another to winch it back in, along with the circuitry and batteries to drive them was no mean feat. It’s impressive they fit it all inside the replica handle; even more impressive that they fit a speaker so this prop even makes the iconic sound effects. We always wanted to see a stage production of William Shakespeare’s Star Wars, and this gives us verily, a new hope.

[HeroTech] isn’t done yet– while seemingly impossible, this lightsaber isn’t perfect, as it’s not rugged enough for full dueling. It’s also not easy to put together, and apparently can’t handle the delicate attentions of airline baggage handlers. So ruggedization and a bit of design-for-assembly are on the table for the next version. Sadly the project is not open source; they are releasing the build files to subscribers only. Given how much work must have gone into iterating to get to this point, that is disappointing, but understandable. Everybody needs to make a living, after all.

If this project seems familiar, it’s because we featured a much-bulkier previous iteration last year.

You may prefer your lightsabers to match the movie version in effects instead of visuals; if that’s the case, check out this saber that uses HHO to cut through a steel door.

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Medium Format, 3 GigaPixel Camera Puts It All On The Line (Sensor)

November 7, 2025 by Tyler August 18 Comments

It’s a bit of a truism that bigger sensors lead to better pictures when it comes to photography. Of course everyone who isn’t a photographer knows that moar megapixles is moar better. So, when [Gigawipf], aka [Yannick Richter] wanted to make a camera, he knew he had to go big or go home. So big he went: a medium format camera with a whopping 3.2 gigapixel resolution.

Now, getting a hold of a sensor like that is not easy, and [Yannick] didn’t even try. The hack starts by tearing down a couple of recent-model Kodak scanners from eBay to get at those sweet CCD line sensors. Yes, this is that classic hack: the scanner camera. Then it’s off to the oscilloscope and the datasheet for some serious reverse-engineering to figure out how to talk to these things. Protocol analysis starts about 4 minutes in of the embedded video, and is worth watching even if you have no interest in photography.

As for what the line sensor will be talking to, why, it’s nothing other than a Rasberry Pi 5, interfacing through a custom PCB that also holds the stepper driver. Remember this is a line sensor camera: the sensor needs to be scanned across the image plane inside the camera, line by line, just as it is in the scanner. He’s using off-the-shelf linear rails to do that job. Technically we suppose you could use a mirror to optically scan the image across a fixed sensor, but scanner cameras have traditionally done it this way and [Yannick] is keeping with tradition. Why not? It works.

Since these images are going to be huge an SD card in the Pi doesn’t cut it, so this is perhaps the only camera out there with an NVMe SSD. The raw data would be 19 GB per image, and though he’s post-processing on the fly to PNG they’re still big pictures. There probably aren’t too many cameras sporting 8″ touchscreens out there, either, but since the back of the thing is so large, why not? There’s still a CSI camera inside, too, but in this case it’s being used as a digital viewfinder. (Most of us would have made that the camera.) The scanner cam is, of course, far too slow to generate its own previews. The preview camera actually goes onto the same 3D-printed mount as the line sensor, putting it onto the same focal plane as the sensor. Yes, the real-time previews are used to focus the camera.

In many ways, this is the nicest scanner camera we’ve ever featured, but that’s perhaps to be expected: there have been a lot of innovations to facilitate this build since scanner cams were common. Even the 3D printed and aluminum case is professional looking. Of course a big sensor needs a big lens, and after deciding projector lenses weren’t going to cut it, [Yannick] sprung for Pentax 6×7 system lenses, which are made for medium format cameras like this one. Well, not exactly like this one– these lenses were first made for film cameras in the 60s. Still, they offer a huge image, high-quality optics, and manual focus and aperture controls in a format that was easy to 3D-print a mount for.

Is it the most practical camera? Maybe not. Is it an impressive hack? Yes. We’ve always had a soft-spot for scanner cameras, and a in a recent double-ccd camera hack, we were lamenting in the comments that nobody was doing it anymore. So we’re very grateful to [Manawyrm] for sending in the tip.

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