A Flip Disc Display That Does It Slow And Steady

August 31, 2026 by Zoe Skyforest 9 Comments

Flip disc displays can be quite a task to drive, what with having some sort of actuator mechanism for each and every dot in the display. [Zimm] has built an altogether different kind of flip disc display, though, which gets around this with a complexity all its own.

The idea behind the build is simple. There is still an array of discs, in this case, 37 x 18 square discs that are black on one side and blue on the other. However, they’re not actuated by magnets or any kind of per-disc flipper. Instead, a CNC machine is charged with flipping them one at a time. There’s a tool head that scans through the array, and uses a color sensor and LIDAR to identify which pixels to flip and how far to push them. It’s not fast, by any means, but it’s a perfectly cromulent way to build a flip disc display, as it turns out.

If you so desire, you can draw or upload images to be displayed on PAR yourself, right from your browser. The project reminds us quite a lot of various plotters we’ve covered over the years, perhaps more than a traditional flip disc display, even.

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Analog Optical Feedback Generates 4K Fractals With No Computer

August 27, 2026 by Tyler August 31 Comments

For users of a certain age, fractal patterns and computers are nearly synonymous. Typing in BASIC programs and seeing the Mandelbrot set or other fractals slowly render on screen is a key memory for some of us. Others will have generated recursive patterns mucking about: point an analog camera at the screen showing its video feed, and you’d better believe you get recursion. It’s called video feedback, and it looks a lot better than audio feedback sounds, especially in the hands of a master like [The Light Herder] who has now found a way to take this vintage art into the 4K resolution of the 21st century.

Physically this build is very similar to the “God Machine II” sculpture we covered previously, which in turn built on the first 720p version of his art piece. Getting analog video feedback in HD was hard enough — you need to be able to adjust the hue, saturation, brightness and contrast of the monitor as you go in order to have the full control of the resulting image. Most old TVs had those back in the SD era, but once HD came around it was rare; [The Light Herder] despaired of ever finding a screen that would to this in 4K.

As it turns out, the answer was to embrace digital — all the knobs on his analog control board feed into a Teensy, which is communicating via RS-232 with the LCD driver boards to alter the desired display properties. Obviously judicious selection of driver boards was required. If you watch the build video embedded below, you’ll find there’s an awful lot of tech in this analog, ‘no computer’ setup. If you want to skip the how-to and a master’s explanation of video feedback and just see pretty pictures he’s got a demo video as well. It really has to be seen to be believed.

If you want to create a colorful analog light show that isn’t quite so self-referential and a lot simpler to build, you could always try soap. Actually, we’d love to see him start the feedback with some soap-film colors. The result would likely be as was once said “totally far out, man”.

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Reject Fluid Simulations, Return To Rheoscopic Fluid

August 25, 2026 by Tyler August 15 Comments

Fluid simulations are one of the “killer apps” of high-performance computing, but if you can’t afford the performance, they can take a depressingly long time to run. Depending on your use case, as long as you keep the Reynold’s number in mind– or are just looking for a qualitative look at pretty flows–you might be able to get away with purely-practical simulations using rheoscopic fluid, as [Visual Thinker] demonstrates in a recent video.

The fluid, as you can guess from the name, lets you scope out rheos— that’s flow, for those of you didn’t take Greek. Making it is as simple as you could ask for: get some mica flakes, which are readily available to add ‘sparkle’ to cosmetics, and mix with water and a drop of soap. The soap isn’t always necessary, but depending on your mica it helps keep it in suspension and avoid clumping– [Visual Thinker] found it helped him a good deal. Being flat plates of reflective material, the mica flakes catch the light and sparkle beautifully– and since they align with the fluid shear, they show you exactly what’s going on in your ‘simulation’.

[Visual Thinker] isn’t starting with serious simulations; the first thing he tries is essentially a toy that lets him see fluid flow around a Benchy by sticking magnets in it and using it to move a cross-section of its hull though a thin layer of fluid sandwitched betwixt pieces of laser-cut acrylic. We don’t call it a toy to disparage it, though– we totally want one. [Visual] mentions the idea of a coffee table combining the concept with the kind of underslung mechanism we see in sand drawing tables, which sounds dangerously hypnotic. If any of you build one, please try and tear your eyes away long enough to let us know.

He has another beautiful piece that make the video worth watching: a wind-tunnel, again made of laser-cut acrylic and printed parts. With careful consideration of the scale and flow speeds, that one might actually prove useful– and even if it doesn’t, it’s pretty enough that it doesn’t really matter. Beauty has its own utility sometimes.

Most wind tunnels we see around here use actual wind, but rheoscopic fluid was invented for this sort of thing, even if it does make for pretty baubles.

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Track Bird Visitors With A Raspberry Pi And A USB Mic

August 8, 2026 by Donald Papp 22 Comments

Avian Visitors is a lovely project by [Teddy Warner] that uses a Raspberry Pi and microphone to keep track of which birds have been visiting your home, and creates a colorful illustration of recent visitors on top of it all.

It reports on a web interface of its own making, but what really takes things to a new level is an optional, stylish E-Ink panel that shows the last 24 hours’ worth of visitors at a glance in a collage.

The key to identification is BirdNET (GitHub here), a deep learning classifier from Cornell that can reliably identify and classify more than 11,000 species worldwide based on sound alone.

Based on that information, the system pulls bird images from a reference set for the region and creates a collage representing the breadth and frequency of visitors in a single image. The larger the image of a bird, the more frequently it was heard.

That’s a cool project, but [Teddy] took things one step further by setting up a color E-Ink display to show a running summary of all the avian visitors the system identifies. [Teddy] has a knack for leveraging projects into wall-mounted art, as we saw with his generative art wall plotter. Continue reading “Track Bird Visitors With A Raspberry Pi And A USB Mic” →

Addressable LEDs Make Giant 16×2 Character Display

August 5, 2026 by Tyler August 12 Comments

We’ve always taken a certain childlike joy in seeing tiny things made big, and big things tiny. Evidently [Uncle Stem] is the same way, if this 7x sized 16×2 “LCD” display is any indicator.

“LCD” is in scare quotes there, because while the original display is a character LCD, [Uncle Stem]’s embigginated recreation is not. Liquid crystal displays are beyond all but the most dedicated DIYers, so [Stem] recreated the whole thing with addressable LEDs instead — over a thousand of them. Each character got its own PCB, and rather than pay for assembly [Stem] used a 3D printed stencil to help apply solder paste, an idea we’ve seen before. His choice of long lengths of nickel strip — the stuff you spot weld to Li-ion batteries — to join the LED-holding PCBs is also worth noting.

In order to get his giant display to act like the I2C-operated module he loves, [Uncle Stem] equipped it with an RP2040 pre-programmed with the LCD character set. That way he can plug it into any Arduino project that uses the LiquidCrystal_I2C library and have the authentic 1602 experience. The green “PCB” the display is mounted to is actually laser-cut plywood, while some acrylic sits in front of his PCBs with office paper to act as as a diffuser. A 3D printed frame completes the illusion. He even goes so far as to replicate the pin headers at 7:1 scaling with brass rods.

He also connects it to a over-sized Arduino, with giant jumper wires. But for the record, not the giant Arduino we featured previously. Like we said, hackers like to mess with scale, and we’ve seen everything from giant benchies to a working Mac Classic for Barbie.

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Scrap Pinball Parts Become Beautiful Wall Art

July 29, 2026 by Zoe Skyforest 2 Comments

[Hans Scharler] came into a neat find recently—the playfield from a 1970s Atari Superman game. It’s the sort of thing that’s too nice to throw away, but isn’t really enough to reassemble into a viable full machine without a great deal of effort. Thus, [Hans] went a different route—turning it into a beautiful piece of wall art.

The first step of the build was to collect missing parts; in particular, all the plastic inserts for the playfield that had been lost at some point. Everything was cleaned up and mounted, along with some modified flippers to complete the look. Custom pop bumpers were 3D printed to act as LED-lit light guides rather than as functional pinball components. [Hans] then set about dotting the board with plenty of WS2811 addressable LEDs in a bullet form factor. Everything was placed under the command of a WLED controller, and it’s synced up to [Hans’s] CheerLights MQTT server to boot. More build details are available on the Pinside post for those eager for a deeper dive.

If you come into some old-school pinball hardware that you’d like to turn into decoration, this project is a great one to study. We’ve featured a few other great pinball builds over the years, too.

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Delta Pen Plotter Draws In Multiple Colors

July 26, 2026 by Zoe Skyforest 15 Comments

If you’re building your first plotter, or you just like thinking in right angles, you’d probably consider a Cartesian design for your build. [András Vujovits] went another route with his project, building an impressive delta pen plotter with a useful tool changer, to boot.

The build relies on a unique motion system, wherein two NEMA 17 stepper motors drive either side of the linkage to control the position of the end effector—in this case, a pen carriage. By controlling the position of each side of the mechanism, it’s possible to move the pen through XY space. Running the show is an Arduino Nano, fitted with a GRBL shield and appropriate stepper motor drivers.

The magnetic tool changer is particularly nifty, too. It allows the plotter to grab a different ink at will to add more color to the drawing. It’s well-designed, with the plotter able to change inks without losing accuracy or otherwise fumbling the switchover. The plotter uses Muji ball point pens, which are available in a range of colors and draw with slick, clean lines. It’s also quite a fast plotter, thanks in part to [András]’s efforts to keep the pen carriage light by using a smart mechanism to offload the pen lifting actuator to the main body.

[András] has plans available, but you’re going to have to pay for them. Still, it’s always nice to see a new machine in the wild. Video after the break.

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