LED Matrix Clock Proudly Shows Its Inner Wiring

March 31, 2026 by Donald Papp 25 Comments

Some projects take great care to tuck away wire hookups, but not [Roberto Alsina]’s Reloj V2 clock. This desktop clock makes a point of exposing all components and wiring as part of its aesthetic. There are no hidden elements, everything that makes it work is open to view. Well, almost.

The exception is the four MAX7219 LED matrices whose faces are hidden behind a featureless red panel, and for good reason. As soon as the clock powers up, the LEDs shine through the thin red plastic in a clean glow that complements the rest of the clock nicely.

[Roberto]’s first version was a unit that worked similarly, but sealed everything away in a wedge-shaped enclosure that was just a little too sterile, featureless, and ugly for his liking. Hence this new version that takes the opposite approach. Clocks have long showcased their inner workings, and electronic clocks — like this circuit-sculpture design — are no exception.

The only components, besides the Raspberry Pi Zero W and the LED matrices, are the 3D-printed enclosure with a few hex screws and double-sided tape. Design files and code (including the FreeCAD project file) are available should you want to put your own spin on [Roberto]’s design.

This Front Panel Makes Its Own Clean-Edged Drill Guides

March 30, 2026 by Donald Papp 8 Comments

We haven’t seen an instrument panel quite like [bluesyann]’s, which was made by curing UV resin directly onto plywood with the help of a 3D printer and a bit of software work. The result is faintly-raised linework that also makes hand drilling holes both cleaner and more accurate.

The process begins by designing the 2D layout in Inkscape, which has the advantage of letting one work in 1:1 dimensions. A 10 mm diameter circle will print as 10 mm; a nice advantage when designing for physical components. After making the layout one uses OpenSCAD to import the .svg and turn it into a 3D model that’s 0.5 mm tall. That 3D model gets loaded into the resin printer, and the goal is to put it directly onto a sheet of plywood.

A little donut shape makes a drill centering feature, and the surrounding ring keeps the edges of the hole clean.

To do that, [bluesyann] sticks the plywood directly onto the 3D printer’s build platform with double-sided tape. With the plywood taking the place of the usual build surface, the printer can cure resin directly onto its surface. Cleanup still involves washing uncured resin off the board, but it’s nothing a soak in isopropyl alcohol and an old toothbrush can’t take care of.

[bluesyann] has a few tips for getting the best results, and one of our favorites is a way to make drilling holes easier and cleaner. Marking the center of a drill hit with a small donut-shaped feature makes a fantastic centering guide, making hand drilling much more accurate. And adding a thick ring around the drill hole ensures clean edges with no stray wood fibers, so no post-drilling cleanup required. Don’t want the ring to stick around after drilling? Just peel it off. There’s a load of other tips too, so be sure to check it out.

A nice front panel really does make a project better, and we’ve seen many different approaches over the years. One can stick laminated artwork onto an enclosure, or one can perform toner transfer onto 3D printed surfaces by putting the design on top of the 3D printer’s build surface, and letting the heat of molten plastic do the work of transferring the toner. And if one should like the idea of a plywood front panel but balk at resin printing onto it, old-fashioned toner transfer works great on wood.

Recreating One Of The First Hackintoshes

March 30, 2026 by Bryan Cockfield 22 Comments

Apple’s Intel era was a boon for many, especially for software developers who were able to bring their software to the platform much more easily than in the PowerPC era. Macs at the time were even able to run Windows fairly easily, which was unheard of. A niche benefit to few was that it made it much easier to build Hackintosh-style computers, which were built from hardware not explicitly sanctioned by Apple but could be tricked into running OSX nonetheless. Although the Hackintosh scene exploded during this era, it actually goes back much farther and [This Does Not Compute] has put together one of the earliest examples going all the way back to the 1980s.

The build began with a Macintosh SE which had the original motherboard swapped out for one with a CPU accelerator card installed. This left the original motherboard free, and rather than accumulate spare parts [This Does Not Compute] decided to use it to investigate the Hackintosh scene of the late 80s. There were a few publications put out at the time that documented how to get this done, so following those as guides he got to work. The only original Apple part needed for this era was a motherboard, which at the time could be found used for a bargain price. The rest of the parts could be made from PC components, which can also be found for lower prices than most Mac hardware. The cases at the time would be literally hacked together as well, but in the end a working Mac would come out of the process at a very reasonable cost.

[This Does Not Compute]’s case isn’t scrounged from 80s parts bins, though. He’s using a special beige filament to print a case with the appropriate color aesthetic for a computer of this era. There are also some modern parts that make this style computer a little easier to use in today’s world like a card that lets the Mac output a VGA signal, an SD card reader, and a much less clunky power supply than the original would have had. He’s using an original floppy disk drive though, so not everything needs to be modernized. But, with these classic Macintosh computers, modernization can go to whatever extreme suits your needs.

Thanks to [Stephen] for the tip!

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Use A Gap-Cap To Embed Hardware In Your Next 3D Print

March 27, 2026 by Donald Papp 20 Comments

Embedding fasteners or other hardware into 3D prints is a useful technique, but it can bring challenges when applied to large or non-flat objects. The solution? Use a gap-cap.

The gap-cap technique is essentially a 3D printed lid. One pauses a print, inserts hardware, then covers it with a lid before resuming the print. The lid — or gap-cap — does three things. It seals in the part, it fills in empty space left above the component, and it provides a nice flat surface for subsequent layers which makes the whole process much cleaner and more reliable.

This whole technique is a bit reminiscent of the idea of manual supports, except that the inserted piece is intended to be sealed into the print along with the embedded hardware under it.

If you have never inserted anything larger than a nut or small magnet into a 3D print, you may wonder why one needs to bother with a gap-cap at all. The short version is that what works for printing over small bits doesn’t reliably carry over to big, odd-shaped bits.

For one thing, filament generally doesn’t like to stick to embedded hardware. As the size of the inserted object increases, especially if it isn’t flat, it increasingly complicates the printer’s ability to seal it in cleanly. Because most nuts are small, even if the printer gets a little messy it probably doesn’t matter much. But what works for small nuts won’t work for something like an LED strip mounted on its side, as shown here.

Cross-section of a print with an embedded LED strip. The print pauses (A), LED strip is inserted and capped with a gap-cap (B, C), then printing resumes and completes (D).

In cases like these a gap-cap is ideal. By pre-printing a form-fitting cap that covers the inserted hardware, one provides a smooth and flat surface that both seals the component in snugly while providing an ideal surface upon which to resume printing.

If needed, a bit of glue can help ensure a gap-cap doesn’t shift and cause trouble when printing resumes, but we can’t help but recall the pause-and-attach technique of embedding printed elements with the help of a LEGO-like connection. Perhaps a gap-cap designed in such a way would avoid needing any kind of adhesive at all.

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.

Ebike Charges At Car Charging Stations

March 5, 2026 by Bryan Cockfield 18 Comments

Electric vehicles are everywhere these days, and with them comes along a whole slew of charging infrastructure. The fastest of these are high-power machines that can deliver enough energy to charge a car in well under an hour, but there are plenty of slower chargers available that take much longer. These don’t tend to require any specialized equipment which makes them easier to install in homes and other places where there isn’t as much power available. In fact, these chargers generally amount to fancy extension cords, and [Matt Gray] realized he could use these to do other things like charge his electric bicycle.

To begin the build, [Matt] started with an electric car charging socket and designed a housing for it with CAD software. The housing also holds the actual battery charger for his VanMoof bicycle, connected internally directly to the car charging socket. These lower powered chargers don’t require any communication from the vehicle either, which simplifies the process considerably. They do still need to be turned on via a smartphone app so the energy can be metered and billed, but with all that out of the way [Matt] was able to take his test rig out to a lamppost charger and boil a kettle of water.

After the kettle experiment, he worked on miniaturizing his project so it fits more conveniently inside the 3D-printed enclosure on the rear rack of his bicycle. The only real inconvenience of this project, though, is that since these chargers are meant for passenger vehicles they’re a bit bulky for smaller vehicles like e-bikes. But this will greatly expand [Matt]’s ability to use his ebike for longer trips, and car charging infrastructure like this has started being used in all kinds of other novel ways as well.

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Computer Terminal Replica Inspired By 70s Hardware

March 1, 2026 by Bryan Cockfield 11 Comments

Not so long ago, most computer users didn’t own their own machines. Instead, they shared time on mainframes or servers, interacting with this new technology through remote terminals. While the rise of cloud computing and AI might feel like a modern, more dystopian echo of that era, some look back on those early days with genuine fondness. If you agree, check out this 70s-era terminal replica from [David Green].

The inspiration for this build was a Lear Siegler ADM-3A terminal seen at a local computer festival. These machines had no local computing resources and were only connected to their host computer via a serial connection. The new enclosure, modeled on this design, was 3D-printed and then assembled and finished for the classic 70s look. There are a few deviations from a 70s terminal, though: notably, a flat LCD panel and a Raspberry Pi 3, which, despite being a bit limited by today’s standards, still offers orders of magnitude more computing power than the average user in the 70s would have had access to.

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