If you’re into pushing tech boundaries from home, this one’s for you. Redditor [mi_kotalik] has crafted ‘Zero’, a custom pair of DIY augmented reality (AR) glasses using a Raspberry Pi Zero. Designed as an affordable, self-contained device for displaying simple AR functions, Zero allows him to experiment without breaking the bank. With features like video playback, Bluetooth audio, a teleprompter, and an image viewer, Zero is a testament to what can be done with determination and creativity on a budget. The original Reddit thread includes videos, a build log, and links to documentation on X, giving you an in-depth look into [mi_kotalik]’s journey. Take a sneak peek through the lens here.

Creating Zero wasn’t simple. From designing the frame in Tinkercad to experimenting with transparent PETG to print lenses (ultimately switching to resin-cast lenses), [mi_kotalik] faced plenty of challenges. By customizing SPI displays and optimizing them to 60 FPS, he achieved an impressive level of real-time responsiveness, allowing him to explore AR interactions like never before. While the Raspberry Pi Zero’s power is limited, [mi_kotalik] is already planning a V2 with a Compute Module 4 to enable 3D rendering, GPS, and spatial tracking.

Zero is an inspiring example for tinkerers hoping to make AR tech more accessible, especially after the fresh news of both Meta and Apple cancelling their attempts to venture in the world of AR. If you are into AR and eager to learn from an original project like this one, check out the full Reddit thread and explore Hackaday’s past coverage on augmented reality experiments.

It takes but an ill-fated second to break a bone, and several long weeks for it to heal in a cast. And even if you have one of those newfangled fiberglass casts, you still can’t get the thing wet, and it’s gonna be itchy under there because your skin can’t breathe. Isn’t it high time for something better?

Enter Cast21, co-founded by Chief Technical Officer [Jason Troutner], who has been in casts more than 50 times due to sports injuries and surgeries. He teamed up with a biomedical design engineer and an electrical engineer to break the norms associated with traditional casts and design a new solution that addresses their drawbacks.

So, how does it work already? The latticework cast is made from a network of silicone tubes that harden once injected with resin and a catalyst mixture. It takes ten seconds to fill the latticework with resin and three minutes for it to cure, and the whole process is much faster than plaster or fiberglass.

This new cast can be used along with electrical stimulation therapy, which can reduce healing time and prevent muscle atrophy.

Cast21 is not only breathable, it’s also waterproof, meaning no more trash bags on your arm to take a shower. The doctor doesn’t even need a saw to remove it, just cut in two places along the seam. It can even be used as a splint afterward.

It’s great to see advancements in simple medical technologies like the cast. And it looks almost as cool as this 3D-printed exoskeleton cast we saw ten years ago.

Thanks to [Keith Olson] for the tip!

Making something enjoyable often requires a clever trick. It could be a way to cut something funny or abuse some peripheral in a way it was never designed for. Especially good tricks have a funny way of coming up again and again. [DERAILED3D] put a 3d printed benchy in a bottle with one of the best tricks 3d printing has.

The trick is stopping the print part way through and tweaking it. You can add manual supports or throw in some PTFE beads to make a generator. The benchy isn’t the print being paused; the bottle is. The benchy is a standard print, and the bottle is clear resin. Once halfway through, they paused the print, and the benchy was left suspended in the bottle with a bit of wire. Of course, [DERAILED3D] moved quickly as they risked a layer line forming on the delicate resin after a minute or two of pausing. The difficulty and mess of tweaking a gooey half-finished resin print is likely why we haven’t seen many attempts at playing with the trick, but we look forward to more clever hacks as it gets easier.

The real magic is in the post-processing of the bottle to make it look as much like glass as possible. It’s a clever modern twist on the old ship in the bottle that we love. Video after the break.

The smell of resin SLA printing is like the weather — everybody complains about it, but nobody does anything about it. At least until now, as [Aris Alder] tackles the problem with an affordable DIY supplied-air respirator.

Now, we know what you’re thinking, anything as critical as breathing is probably best left to the professionals. While we agree in principle, most solutions from reputable companies would cost multiple thousands of dollars to accomplish, making it hard to justify for a home gamer who just doesn’t want to breathe in nasty volatile organic compounds. [Aris] starts the video below with a careful examination of the different available respirator options, concluding that a supplied air respirator (SAR) is the way to go.

His homebrew version consists of an affordable, commercially available plastic hood with a built-in visor. Rather than an expensive oil-free compressor to supply the needed airflow, he sourced a low-cost inline duct fan and placed it outside the work zone to pull in fresh air. Connecting the two is low-cost polyethylene tubing and a couple of 3D printed adapters. This has the advantage of being very lightweight and less likely to yank the hood off your head, and can be replaced in a few seconds when it inevitably punctures.

Another vital part of the kit is a pulse oximeter, which [Aris] uses to make sure he’s getting enough oxygen. His O₂ saturation actually goes up from his baseline when the hood is on and powered up, which bodes well for the system. Every time we pick up the welding torch or angle grinder we wish for something like this, so it might just be time to build one.

Thanks to [Zane Atkins] for the tip.

[Colleen] struggled with using a chef’s knife to cut a variety of foods while suffering from arthritis in her wrist and hand. There are knives aimed at people with special needs, but nothing suitable for serious work like [Colleen]’s professional duties in a commercial kitchen.

As a result, the IATP (Illinois Assistive Technology Program) created the Adaptive Chef’s Knife. Unlike existing offerings, it has a high-quality blade and is ergonomically designed so that the user can leverage their forearm while maintaining control.

The handle is durable, stands up to commercial kitchen use, and is molded to the same standards as off-the-shelf knife handles. That means it’s cast from FDA-approved materials and has a clean, non-porous surface. The pattern visible in the handle is a 3D printed “skeleton” over which resin is molded.

Interested? The IATP Maker Program makes assistive devices available to Illinois residents free of charge (though donations in suggested amounts are encouraged for those who can pay) but the plans and directions are freely available to anyone who wishes to roll their own.

Assistive technology doesn’t need to be over-engineered or frankly even maximally efficient in how it addresses a problem. Small changes can be all that’s needed to give people meaningful control over the things in their lives in a healthy way. Some great examples are are this magnetic spoon holder, or simple printed additions to IKEA furnishings.

Way to rub it in, guys. As it turns out, due to family and work obligations we won’t be able to see the next Great American Eclipse, at least not from anywhere near the path of totality, when it sweeps from Mexico into Canada on April 8. And that’s too bad, because compared to the eclipse back in 2017, “Eclipse 2: Solar Boogaloo” is occurring during a much more active phase in the solar cycle, with the potential for some pretty exciting viewing. The sun regularly belches out gigatons of plasma during coronal mass ejections (CMEs), most of which we can’t see with the naked eye because not only is staring at the sun not a great idea, but most of that activity occurs across the disk of the sun, obscuring the view in the background light. But during the eclipse, we — oops, you — might just get lucky enough to have a solar prominence erupt along the limb of the sun that will be visible during totality. The sun has been quite active lately, as reflected by the relatively high sunspot number, so even though it’s an outside chance, it’s certainly more likely than it was in 2017. Good luck out there. 

Those of us not in the path of totality in two weeks aren’t all out of luck, though — we still might have a chance to see a star go nova. And no, this won’t be the much-anticipated supernova death of Betelgeuse, which despite ominous portents to the contrary is still probably thousands of years away. Instead, what’s coming up is the latest outburst in a repeating 80-year cycle of novas in the constellation Corona Borealis, or the Northern Crown. The system has a binary star called T Coronae Borealis, a white dwarf and a red giant locked in a death spiral with each other. Normally the red giant dominates, but about every 80 years the white dwarf sucks enough material from the red giant to start really shining, markedly increasing the luminosity of the system. Current predictions are for the nova to start somewhere between now and September. Finding it should be easy, as long as you live in the Northern Hemisphere; just find Arcturus — “Follow the arc to Arcturus” — and then continue the arc to the nearby U-shaped assembly of stars that make up the Northern Crown. The nova will be visible to the naked eye in that constellation. It won’t be supernova spectacular, but hey — it’s something.

And wrapping up space news this week, we stumbled across a story about a no good, very bad day for someone at Lockheed Martin back in 2003. The accident involved the National Oceanic and Atmospheric Administration’s NOAA N-Prime satellite, which was under construction at the time. During a maneuver to turn the satellite from vertical to horizontal, the satellite crashed onto the cleanroom floor, resulting in $135 million in damages. A post-mortem analysis revealed that a technician had removed 24 bolts from the “turn-over cart” while it was in storage, but failed to document the fact. Lumping it all on that poor tech isn’t fair, though, since the N-Prime team didn’t bother to check whether the bolts were installed before flipping the bird. The repaired satellite eventually made it to orbit as NOAA-19 in 2009, and is still in service 15 years later. Not too bad for something that could very easily have been junked.

Are you worried that you have too many non-humans in your life? No, we’re not talking about people with too many cats or an undue attachment to their “Fur Babies,” but to those of us with too many bots in our lives, especially on social media. Luckily, there’s an easy way to check if your online interlocutors are actually humans: R U Human. It’s a site that lets you create a custom URL that you can forward to suspected bots, who have to fill in their name and complete a Captcha. If they pass the test, their verification is recorded for you to inspect. We’re rarely a fan of filling out Captchas and are loathe to force someone else to do so, but such are the times we live in, apparently.

And finally, if you’re not just a little grossed out by the way shellac is produced, you probably will be once you realize how much of the natural thermoplastic you consume in a year. We’d learned long ago that shellac is produced by the lac bug (Kerria lacca), but seeing just how it’s harvested is fascinating. Not to mention the fact that lac farmers are very much in the animal husbandry business, with insects being their livestock rather than goats or chickens. The amount of manual work that goes into harvesting, cleaning, melting, and purifying shellac is incredible, as is the number of products it ends up in, including candies, pharmaceuticals, and citrus fruits. Yum!

[Thomas TEMPE] has been making two-color resin prints. While printing in multiple colors is old hat for FDM printers, the way resin printers work makes it a more difficult proposition. [Thomas] has a simple solution. First, he prints an item with a cavity where he would like the second color. Then, after printing, he fills the cavity with a different color resin using a syringe and cures it. Simple, really.

Of course, it is all about technique. For fine lines, you’ll want a smaller needle, and you flood the area with the alternate resin and wipe away the excess. For wider lines, you simply fill the cavity from a larger syringe.

Thomas uses this to produce high-contrast text. However, it occurs to us you could do anything that was embossed into the original print. It doesn’t have to be text. There’s also no reason you have to use only one color of fill resin.

We’ve seen resin used to smooth FDM prints. We wonder if you could print the base using FDM and use this technique to add colorful resin highlights. If you try it, drop us a note.

This would be great for custom keycaps. We’ve seen keycaps printed with an air-dry clay inlay.