This Printed Zipper Repair Requires No Unsewing

March 14, 2026 by Donald Papp 20 Comments

If a zipper breaks, a 3D printer might not be the first tool one reaches for — but it’s more feasible than one might think. [MisterJ]’s zipper slider replacement is the kind of 3D print that used to be the domain of well-tuned printers only, but most hobbyist printers should be able to handle it nowadays.

The two-part design allows installation without unsewing the zipper ends. Note the print orientation of the green part, which maximizes the strength of the peg by making the layer lines perpendicular to the load.

What really sets this design apart from other printed versions is its split construction. Putting a new slider onto a zipper usually requires one to free the ends of the zipper by unsewing them. [MisterJ]’s two-part design instead allows the slider to be assembled directly onto the zipper, without the hassle of unsewing and re-sewing anything. That’s a pretty significant improvement in accessibility.

Want to make some adjustments? Good news, because the files are in STEP format which any CAD program will readily understand. We remember when PrusaSlicer first gained native STEP support and we’re delighted that it’s now a common feature in 3D printer software.

[MisterJ]’s zipper slider design is available in a variety of common sizes, in both standard (zipper teeth face outward) and reverse (zipper teeth face inward) configurations. Naturally a metal slider is more durable than a plastic one, but being able to replace broken parts of a zipper with a 3D printer is a pretty handy thing. Speaking of which, you can also 3D print a zipper box replacement should the squarish bit on the bottom get somehow wrecked or lost.

Evolved Nerf RC Tank Now Leaves Welts

February 27, 2026 by Donald Papp 6 Comments

[Joshua Clay] recently unveiled his newest RC Nerf Dart Robot and talks through his design choices, pointing out that in his aim to have it launch darts fast and hard he may have somewhat overshot the mark. He found out first hand during testing that it shoots hard enough to leave welts through a sweatshirt and probably should be downgraded a bit. Thankfully, one of the features of his new unit is a highly modular design that makes iterating easier than ever.

A modular, glue-free assembly that leaves wiring accessible helps make design iterations faster and easier.

This model is an evolution of his first Nerfbot, and the new one is a smaller, tighter design that trades a wheeled base for a tracked one, among other changes.

The tank platform is one example of [Joshua] using affordable, off-the-shelf solutions where it makes sense to do so. For example, the inexpensive tank-track platform means he can focus on the rest of the bot without having to design or make his own tank treads. Similarly, to control the bot he opts for a PlayStation 4 controller, paired to the bot over Bluetooth. It’s high quality, inexpensive, commonly available, and easily interfaced with the RP2040 that runs the show.

[Joshua] aims for a modular, LEGO-inspired mechanical assembly that makes maintenance, wiring, and iteration as easy as possible. We especially like how the battery, wiring, and things like gears for the pan-and-tilt mechanism of the Nerf launcher are easily accessible.

The dart launcher uses two flywheels to grip and propel each dart fed from a high-capacity magazine, and you can watch it move and shoot around the 9:44 mark in the video, embedded below. It’s plenty loud, but the camera is barely able to register darts leaving the barrel.

If you like the looks of [Joshua]’s newest Nerfbot, keep an eye out because he’s got more to share about it and is considering other features like a camera. In the meantime, there are a few more photos on his website.

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Let Hauntimator Steer Your Next Animatronic Display

February 27, 2026 by Donald Papp 2 Comments

Animatronic displays aren’t just for Halloween, and hackers today have incredible access to effective, affordable parts with which to make spectacles of light, sound, and movement. But the hardware is only half the battle. Getting everything synchronized properly can be a daunting task, so get a head start on your next holiday display with the Hauntimator by [1031-Systems].

Synchronizing control channels to audio is at the heart of solid animations.

After all, synchronizing movements, sound, and light by trial and error can get tiresome even in small setups. Anyone who makes such a display — and contemplates doing it twice — tends to quickly look into making things modular.

At its heart, Hauntimator works with a Raspberry Pi Pico-based controller board. The GUI makes it easy to create control channels for different hardware (for example, doing things like moving servos) and synchronize them to audio. Once an animation is validated, it gets uploaded to the control board where it runs itself. It’s open-source and designed to make plugins easy, so give it a look. There’s a video channel with some demonstrations of the tools that should fill in any blanks.

Intrigued by animatronics, but not sure where to begin? Get inspired by checking out this DIY set of servo-driven eyes, and see for yourself the benefits of smooth motor control for generating lifelike motion.

Robot Looks Exactly Like A Roll Of Filament, If Filament Had Eyes

February 26, 2026 by Donald Papp 2 Comments

[Matt Denton]’s SpoolBot is a surprisingly agile remote-controlled robot that doesn’t just repurpose filament spool leftovers. It looks exactly like a 2 kg spool of filament; that’s real filament wound around the outside of the drum. In fact, Spoolie the SpoolBot looks so much like the real thing that [Matt] designed a googly-eye add-on, because the robot is so easily misplaced.

The robot’s mass rotates around a central hub in order to move forward or back.

SpoolBot works by rotating its mass around the central hub, which causes it to roll forward or back. Steering is accomplished by tank-style turning of the independent spool ends. While conceptually simple, quite a bit of work is necessary to ensure SpoolBot rolls true, and doesn’t loop itself around inside the shell during maneuvers. Doing that means sensors, and software work.

To that end, a couple of rotary encoders complement the gearmotors and an IMU takes care of overall positional sensing while an ESP32 runs the show. The power supply uses NiMH battery packs, in part for their added weight. Since SpoolBot works by shifting its internal mass, heavier batteries are more effective.

The receiver is a standard RC PWM receiver which means any RC transmitter can be used, but [Matt] shows off a slick one-handed model that not only works well with SpoolBot but tucks neatly into the middle of the spool for storage. Just in case SpoolBot was not hard enough to spot among other filament rolls, we imagine.

The googly-eye add-on solves that, however. They clip to the central hub and so always show “forward” for the robot. They do add quite a bit of personality, as well as a visual indication of the internals’ position relative to the outside.

The GitHub repository and Printables page have all the design files, and the video (embedded just below) shows every piece of the internals.

The kind of hardware available nowadays makes self-balancing devices much more practical and accessible than they ever have been. Really, SpoolBot has quite a lot in common with other self-balancing robots and self-balancing electric vehicles (which are really just larger, ridable self-balancing robots) so there’s plenty of room for experimentation no matter one’s budget or skill level.

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Bionode Is Hand Truck Transformed Into Mobile Computing Lab

February 26, 2026 by Donald Papp 13 Comments

[Steven K. Roberts] is the original digital nomad, having designed and built mobile computing for his own use since the 80s. His latest project is Bionode, a portable computing lab built into a hand truck that can accommodate a wide spectrum of needs for a person on the go.

Far more than just a portable computer with wheels and a handle, Bionode is an integrated collection of systems with power management, a sensor suite, multiple computers, NAS for storage, networking, video production tools, and even the ability to be solar charged. [Steven] also uses a laptop, and Bionode complements it by being everything else.

If one truly wishes to be mobile and modular as well as effective, then size and weight begins to be just as important as usability. Everything in Bionode has a purpose, and it currently contains a PC with GPU for local AI and machine learning work, a NAS with 14 TB of storage, an Ubuntu machine, a Raspberry Pi 5 running Home Assistant, another Raspberry Pi 5 for development work, a Raspberry Pi 3 for running his 3D printer, and a Raspberry Pi 4 for SDR (software-defined radio) work. A smart KVM means a single keyboard, mouse, and display can be shared among machines as needed and additional hardware in a thoughtful layout makes audio and video projects workable. Everything is integrated with sensors and Home Assistant with local AI monitoring, which [Steven] likes to think of as the unit’s nervous system.

Bionode is therefore more than just a collection of computers crammed into a hand truck; it’s a carefully-selected array of hardware that provides whatever [Steven] needs.

Give it a look if you want to see what such a system looks like when it’s been designed and assembled by someone who’s “been there, done that” when it comes to mobile computing. Bionode would complement something like a mobile workshop quite nicely; something [Steven] has also done before.

Thanks [Paul] for the tip!

Custom Clamshell Cyberdeck Shows Off Underlighting

February 13, 2026 by Donald Papp 19 Comments

Cyberdecks are great projects, and [Salim Benbouziyane]’s scratch-built CM Deck is a fantastic specimen. It’s a clamshell-style cyberdeck with custom split keyboard, trackpad, optional external WiFi antenna, and some slick underlighting thanks to a translucent bottom shell. There’s even a hidden feature that seems super handy for a cyberdeck: a special USB-C port that, when plugged in to another host (like another computer), lets the cyberdeck act as an external keyboard and trackpad for that downstream machine.

The CM Deck is built around the Raspberry Pi Compute Module 5, which necessitates a custom PCB but offers more design freedom.

Notably, the CM Deck is custom-built around the Raspberry Pi Compute Model 5. When we first peeped the CM5 the small size was striking, but of course that comes at the cost of having no connectors, supporting hardware, or heat management. That’s something [Salim] embraced because it meant being able to put connectors exactly where he wanted them, and not have to work around existing hardware. A custom PCB let him to lay out his cyberdeck with greater freedom, less wasted space, and ultimately integrate a custom-built keyboard (with RP2040 and QMK firmware).

Even the final enclosure is custom-made, with 3D printing being used to validate the design and PCBway providing finished plastic shells in addition to manufacturing the PCBs. [Salim] admits that doing so was an indulgence, but his delight at the quality of the translucent purple undercarriage is palpable.

[Salim]’s video (embedded below) is a deep dive into the whole design and build process, and it’s a great watch for anyone interested in the kind of work and decisions that go into making something like this. Experienced folks can expect to nod in sympathy when [Salim] highlights gotchas like doing CAD work based on the screen’s drawings, only to discover later that the physical unit doesn’t quite match.

The GitHub repository contains the design files for everything, so give it a browse if you’re interested. [Salim] is no stranger to clean builds, so take a moment to admire his CRT-style Raspberry Pi terminal as well.

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Welding Nuts Inside Metal Tubes, Painlessly

February 6, 2026 by Donald Papp 37 Comments

[Jer Schmidt] needed a way to put a lot of M8 bolts into a piece of square steel tubing, but just drilling and tapping threads into the thin steel wouldn’t be strong enough. So he figured out a way to reliably weld nuts to the inside of the tube, and his technique works even if the tube is long and the inside isn’t accessible.

Two smaller holes on either side. Weld through the holes. A little grinding results in a smooth top surface.

Essentially, one drills a hole for the bolt, plus two smaller holes on either side. Then one welds the nut to the tubing through those small holes, in a sort of plug weld. A little grinding is all it takes to smooth out the surface, and one is left with a strong threaded hole in a thin-walled tube, using little more than hardware store fasteners.

The technique doesn’t require access to the inside of the tube for the welding part, although getting the nut back there in the first place does require a simple helper tool the nut can slot into. [Jer] makes one with some scrap wood and a table saw, just to show it doesn’t need to be anything fancy.

Another way to put a threaded hole into thin material is to use a rivnut, or rivet nut (sometimes also used to put durable threads into 3D prints) but welding a plain old nut to the inside was far more aligned with what [Jer] needed, and doesn’t rely on any specialty parts or tools.

[Jer]’s upcoming project requires a lot of bolts all the way down long tubing, which is what got him into all of this. Watch it in action in the video below, because [Jer] has definitely worked out the kinks, and he steps through a lot of tips and tricks to make the process painless.

Thanks [paulvdh] for the tip!

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