Author: Donald Papp

1343 Articles

Calculator UI Is More Complex Than You Might Think

July 18, 2026 by 24 Comments

Calculators are so ubiquitous and so familiar that they are easy to take for granted in many different ways. [lcamtuf] points out one that has probably never occurred to many of us: the user interface for a calculator is an unexpectedly complex thing.

The internal logic to support sequential inputs and multiple operators in a way that feels intuitive is a complex thing.

Resolving something like 1 + 2 = is pretty straightforward but complexity compounds rapidly after that, with numerous special cases. Let’s imagine one decides to program a simple calculator UI as a weekend project. The development process might look a little like this:

  1. User types in 1 + 2 = and the calculator displays 3. What happens if the user immediately presses -?
  2. No problem, just consider the result of the previous operation as an already-there input. So we’ll have 3 - for this next operation, and wait for more.
  3. Unless we should have treated that - as a negative sign for whatever number is coming next, making it a negative number? No, ignore that. Just treat whatever results from pressing equals as a pre-typed input.
  4. Unless the user hits a number. Because if they hit 2 (for example) then we’ll have a 32 and not a 2 which they probably, definitely don’t expect. So that’s a special case and we should insert a clear if that happens.
  5. Oh, better clear if the user enters a decimal, too.
  6. I’m going to need a coffee…

And that’s just the tip of the iceberg. Imagine trying to figure all this out for the very first time, without the benefits of habit and history to fall back on.

The fact is that supporting the apparently trivial behavior of a simple calculator requires an underlying complex state machine that deals with all kinds of special cases in order to make the UI feel intuitive. And that’s just for a basic four-function calculator; we haven’t even touched on how special keys like % should behave.

We know [lcamtuf] speaks from experience, not just because of their deep knowledge of calculator history but because they rolled their own calculator that uses voltmeters as digit displays and there’s nothing like actually implementing something to make one appreciate it.

Spidery Drone Goes Near-invisible By Spinning Really, Really Fast

July 18, 2026 by 27 Comments

Researchers demonstrate that something interesting happens when a small drone with a spindly airframe spins at a high speed: it very nearly turns invisible. The spidery device is shown mounted in its launcher in the image above. The dark blur at the rightmost side is an outlet on the wall behind the drone, not motion blur from a moving part.

There’s not much to do about the noise, but a high-speed spin becomes nearly invisible.

It’s called the Phantom Twist, and while we’ve seen single-motor drones that spin around a central axis before, they have always incorporated a wing-like structure or cleverly leverage the magnus effect to generate lift.

There’s not a lot of detail about the Phantom Twist’s hardware design but it appears to use a downward-angled motor for lift, relying on a high-speed control system to maneuver and maintain altitude.

This does away with the need for a wing, at the cost of only being stable while rotating at a high speed. We imagine it is also a touchy design that depends greatly on being balanced just so.

A hand launcher spins the device up before releasing it for flight. The visual effect once it is up and running is pretty striking; see for yourself in the short video, embedded just below.

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Flex Filament Stuck To Your Build Platform? Reach For The Isopropanol

July 17, 2026 by 9 Comments

3D printing has been around long enough that everyone’s heard at least one weird trick regarding 3D prints. [Angus] of [Maker’s Muse] puts a few to the test, and came away with one solid tip for releasing TPU from a build platform to which it has unfortunately welded itself.

Flexible filaments tend to stick too well to build plates, which is why an interface layer like a thin layer of glue stick is called for. But what if one forgets to apply it before starting a print job? That can result in a print that is well and truly stuck. Peeling flex filament off a textured PEI bed is a bad time, because the print can tear and tends to leave little bits behind.

[Angus] heard that applying isopropyl alcohol helps release things in that case, so he gives it a try. Lo and behold, it seems to work! See for yourself at 18:10 in the video and keep it in mind if you end up in a similar situation. The print doesn’t exactly fall off on its own, but it does remain in one piece which is more than one can expect otherwise.

Watching isopropyl alcohol help release a stuck print is reminiscent of the way it also removes hot glue from just about any surface. The trick is getting the alcohol to wick in underneath for best results, and the same seems to be true with releasing TPU from a build plate.

One thing to keep in mind when evaluating tips and tricks from over the years is that the landscape changes. Something that maybe seemed to have potential years ago might not make much sense today. A good example is sugar as a bed adhesive, which [Angus] tries out. What started as an experiment in getting PLA to play better with glass build plates years ago doesn’t really carry over to now, with PEI-coated magnetic build platforms pretty much a solved problem. The more likely result nowadays is just a mess.

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Cut And Fold Your 3D Printer’s Next Cover

July 15, 2026 by 14 Comments

[cmh]’s ultra-simple top cover for the Snapmaker U1 3D printer has a 3D model, but don’t let that fool you. There’s no 3D printing at all involved in this project. Rather, the model is a reference shape for making an effective top cover out of cardboard or corrugated plastic sheet (also known as Coroplast) which is what [cmh] used.

The pattern can be cut from a single sheet, or from multiple pieces taped together.

Corrugated plastic is a versatile option for things like printer enclosures. It’s cheap, a good insulator, easy to cut, and available from just about any plastics supplier. We’ve made the case that they’re a good alternative to acrylic sheets for printer enclosures, but [cmh] goes even further with a design that requires no additional hardware whatsoever. Assembly doesn’t even require more than tape, really.

He provides a cutout diagram for pieces that, when assembled, make a sort of hat that is just right to cover the top of the Snapmaker U1 without obstructing the extruders. One can even lift the front panel to access the inside without removing the cover, which is a nice touch. Should one wish to add a viewing window anywhere, just cut out a square and tape a sheet of clear plastic over the hole.

For a 3D printer, an enclosure and top cover helps retain heat, block drafts, and keep dust (or curious fingers) away from the printer’s build area. The cover doesn’t need to be completely sealed to deliver those benefits, but if you do prefer your covers completely enclosed, a carefully-chosen IKEA storage box makes a conveniently great cover for the U1.

Full Body VR Tracking Is Just Some Recycled Hardware Away

July 14, 2026 by 11 Comments

Full body tracking in VR applications involves attaching sensors to one’s body, and [Jaki] has a DIY method to do it on the cheap: the Vive Tracker Lite project repurposes Vive controllers as lighthouse-based trackers, no hardware modifications required.

A common method of doing body tracking is to strap on some Vive trackers. Those are extremely hacker-friendly pieces of hardware, but [Jaki] observed that older Vive VR controllers can be had for cheap, and already contain everything a tracker needs. Some new firmware and a custom mount is all it takes to turn them into perfectly usable body trackers.

But what about a wireless receiver? [Jaki] has that covered as well with the $5 Viva Dongle, which uses a Pro Micro NRF52840 to act as a cheap DIY alternative to the official dongle hardware.

We appreciate the effort put into making this project accessible to everyone, even novices. [Jaki]’s put effort into a Python program with a full GUI to make the flashing of firmware as easy as possible for both projects. Experimenting with body tracking in VRChat or games with mods is just some recycled hardware away.

Granted, a Vive controller is not the slimmest piece of hardware, but all it takes is a firmware change and a 3D-printed fixture to make a perfectly serviceable tracker. That being said, we’re sure an enterprising hardware hacker may crack a controller open and embark on a serious rebuild, or even interface to some of the inputs in a clever way. If you’ve done that or know of someone who has, drop us a note on our tips line because we’d love to see it.

Voltmeter-Based Floating Point Calculator Does It In Style

July 13, 2026 by 16 Comments

[lcamtuf] is not just a calculator superfan, but also a skilled builder. That much is evident in the fabulous  design of Calcumator 2000, an electromechanical calculator that uses voltmeter readouts as digits (plus one at the bottom to represent decimal place). There are plenty of high-quality build images, so give it a look!

Meters like the one on the right (numbered 0 to 9) act as digit displays. The meter on the left indicates decimal position.

Calcumator 2000 is a bit of a love letter to a time when display technology hadn’t quite yet produced anything suitable for calculator use. This resulted in calculator designs that are generally unrecognizable compared to the 7-segment display based devices we see today. The Calcumator 2000, in all its electromechanical glory, would have fit right in that era.

The Calcumator 2000 has all the usual buttons one would expect from a simple calculator and drives a total of seven readouts, one of which acts as the decimal point. The idea of using voltmeters as digit displays came from [lcamtuf]’s voltmeter clock, an earlier work with a similar attention to detail in its design and assembly.

We want to take a moment to admire how clean the blue panel is. [lcamtuf] made it by painting one side of an acrylic panel, cutting the letters and design out on a CNC mill, then filling with white paint. The depth of the cuts gives the white elements a nifty multi-layer effect that really complements the design.

Want to see it work? Oh yes, you do. Check out the video, embedded just below.

Continue reading “Voltmeter-Based Floating Point Calculator Does It In Style” →

DIY Steam Controller Puck Offers Xbox, Switch, PlayStation Emulation Modes

July 13, 2026 by 12 Comments

Valve recently released a new version of the Steam Controller, which features a wired USB puck that serves both as charger and dedicated, low-latency wireless receiver. The downside is they aren’t currently available for purchase separately, but that’s not a worry because you can now make your own thanks to [safijari]’s OpenPuck project.

OpenPuck uses the highly affordable Pro Micro NRF52840 board, programmed to emulate the wireless receiver portion of the puck, meaning one can pair their Steam Controller to it just like they would with the factory puck. A major part of the project was naturally documenting the wireless protocol, but there’s also an array of extra features offered by OpenPuck.

OpenPuck offers features over and above the factory offering. [image: 3d printed case by jaki-gh]
Hitting button combos lets one conveniently emulate Xbox, Nintendo Switch, or Sony PlayStation controllers. Meaning OpenPuck can for example be plugged into a Nintendo Switch and it will see OpenPuck as an official wired controller, complete with motion sensor and haptic feedback.

Why is it necessary for this emulation to be done from OpenPuck? Because while the Steam Controller has tight integration with Steam Input — a sort of highly useful translation layer for controller inputs — that integration also means the controller’s best features only work while Steam is running. OpenPuck’s ability to emulate other console controllers makes it flexible in a way the factory puck isn’t, and a user can make the most of a single controller this way.

It’s worth noting that while the real puck has the ability to charge the controller (whether or not the user makes it walk itself), the OpenPuck doesn’t have this ability. Does that mean one must still use the factory puck for charging? Not at all, as the Steam Controller charges just fine over a USB-C connection.

There’s a short video below that demonstrates the flashing and setup, so check it out if you think it might be useful to you.

Continue reading “DIY Steam Controller Puck Offers Xbox, Switch, PlayStation Emulation Modes” →