Author: Lewin Day

3182 Articles

Spin-Casting This Telescope Mirror In Resin Didn’t Go To Plan

June 3, 2025 by 29 Comments

For most of us, mirrors are something we buy instead of build. However, [Unnecessary Automation] wanted to craft mirrors of his own for a custom telescope build. As it turns out, producing optically-useful mirrors is not exactly easy.

For the telescope build in question, [Unnecessary Automation] needed a concave mirror. Trying to get that sort of shape with glass can be difficult. However, there’s such a thing as a “liquid mirror” where spinning fluid forms into a parabolic-like shape. Thus came the idea to spin liquid resin during curing to try and create a mirror with the right shape.

That didn’t quite work, but it inspired a more advanced setup where a spinning bowl and dense glycerine fluid was used to craft a silicone mold with a convex shape. This could then be used to produce a resin-based mirror in a relatively stationary fashion. From there, it was just necessary to plate a shiny metal layer on to the final part to create the mirror effect. Unfortunately, the end result was too messy to use as a viable telescope mirror, but we learn a lot about what didn’t work along the way.

The video is a great journey of trial and error. Sometimes, figuring out how to do something is the fun part of a project, even if you don’t always succeed. If you’ve got ideas on how to successfully spin cast a quality mirror, drop them in the comments below. We’ve seen others explore mirror making techniques before, too.

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3D Printing A Capable RC Car

June 2, 2025 by 7 Comments

You can buy all sorts of RC cars off the shelf, but doing so won’t teach you a whole lot. Alternatively, you could follow [TRDB]’s example, and design your own from scratch.

The Lizard, as it is known, is a fun little RC car. It’s got a vaguely Formula 1-inspired aesthetic, and looks fetching with the aid of two-tone 3D printed parts. It’s designed for speed and handling, with a rear-wheel-drive layout and sprung suspension at all four corners to soak up the bumps. The majority of the vehicle is 3D printed in PETG, including the body and the gearbox and differential. However, some suspension components are made in TPU for greater flexibility and resistance to impact. [TRDB] specified commercial off-the-shelf wheels to provide good grip that couldn’t easily be achieved with 3D-printed tires. An ESP32 is responsible for receiving commands from [TRDB’s] custom RC controller running the same microcontroller. It sends commands to the speed controller that runs the Lizard’s brushed DC motor from a 3S lithium-polymer battery.

The final product looks sleek and handles well. It also achieved a GPS-verified top speed of 48 km/h as per [TRDB’s] testing. We’ve seen some other great DIY RC cars over the years, too, like this example that focuses on performance fundamentals. Video after the break.

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Ender 3 Pro Gets A Second Job As A Stator Winder

June 2, 2025 by 10 Comments

Sometimes, you find yourself in need of a coil. You could sit around winding thousands of turns of copper wire yourself, but that would be remarkably tedious. Thus, instead, you might follow the example of [OJengineering] and choose to get a machine to do it for you.

This build first popped up on on Reddit, with [OJengineering] explaining that they had repurposed an Ender 3 Pro 3D printer to wind a stator for them. The reasoning was sound—a replacement stator for their motorcycle cost $1000 in their local area, so rewinding their own would be much cheaper. The idea was straightforward enough—the 3D printer was a capable motion control platform that really just needed to be retooled to drag wire around instead of squirting hot plastic. In a later update, they explained that they had created a Python program that spits out appropriate stator winding G-code from user-entered parameters. This G-code commands the 3D printer’s head to make rectangle winds around the stator core while moving up and down to appropriately distribute the wire. The device can be seen in action in a video on YouTube.

It’s a hacky build, but one that does nevertheless get the winding done. That’s the thing about 3D printers—they’re really just simple motion systems that can do whatever you tell them. You just need a way to generate the right G-code to do the job.

We’ve featured some other nifty coil winders before, too. Video after the break.

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It’s MIDI For The TRS-80!

June 1, 2025 by 16 Comments

The Radio Shack TRS-80 was a much-loved machine across America. However, one thing it lacked was MIDI. That’s not so strange given the era it was released in, of course. Nevertheless, [Michael Wessel] has seen fit to correct this by creating the MIDI/80—a soundcard and MIDI interface for this old-school beast.

The core of the build is a BluePill STM32F103C8T6 microcontroller, running at a mighty 75 MHz. Plugged into the TRS-80s expansion port, the microcontroller is responsible for talking to the computer and translating incoming and outgoing MIDI signals as needed. Naturally, you can equip it with full-size classic DIN sockets for MIDI IN and MIDI OUT using an Adafruit breakout module. None of that MIDI Thru nonsense, though, that just makes people uncomfortable. The card is fully capable of reproducing General MIDI sounds, too, either via plugging in a Waveblaster sound module to the relevant header, or by hooking up a Roland Sound Canvas or similar to the MIDI/80s MIDI Out socket. Software-wise, there’s already a whole MIDI ecosystem developing around this new hardware. There’s a TRS-80 drum tracker and a synthesizer program, all with demo songs included. Compatibility wise, The MIDI/80 works with the TRS-80 Model I, III, and 4.

Does this mean the TRS-80 will become a new darling of the tracker and chiptune communities? We can only hope so! Meanwhile, if you want more background on this famous machine, we’ve looked into that, too. Video after the break.

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Making The Codec Communicator From Metal Gear Solid

June 1, 2025 by 9 Comments

[3DSage] likes building replicas of hardware from movies and video games, often with a functional twist. His latest build aimed to bring the Codec from Metal Gear Solid to life.

If you haven’t played the Metal Gear games, the Codec has been modelled somewhat like an advanced walkie talkie at times, but has often been kept off-screen. Thus, [3DSage] had a great deal of creative latitude to create a realistic-feeling Codec device that provided voice communications and some simple imagery display.

The resulting build relies on an RP2040 microcontroller to run the show. It’s paired with an MPU6050 3-axis gyroscope and accelerometer for motion control of the device’s functionality, and features a small LCD screen to mimic the display in the games. A kids walkie-talkie kit was leveraged for audio communication, but kitted out with a better microphone than standard. Power is via a rechargeable 9V battery, which is really a lithium-ion and USB charging board packed into the familiar 9V form factor.

Where the build really shines, though, is the aesthetic. [3DSage] managed to capture the military-like look and feel as well as authentically recreate the graphics from the games on the screen. The simulated noise on the display is particularly charming. Beyond that, the 3D-printed enclosures leverage texture and multi-color printing really well to nail the fit and finish.

Ultimately, the Codec isn’t much more than a glorified walkie talkie. Even still, [3DSage] was able to create an impressive prop that actually does most of what the device can do in game. If you’ve ever coveted a PipBoy or tricorder, this is one project you’ll be able to appreciate.

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Portal 2 Becomes An Impressively Capable Web Server

June 1, 2025 by 5 Comments

Portal 2 is mostly known as the successful sequel to Valve’s weird physics platformer, Portal. It’s not really known for being a webserver. That might change, though, given the hard work of [PortalRunner].

Quite literally, [PortalRunner] hacked the Source engine and Portal 2 to actually run a working HTTP web server. That required setting up the code to implement a TCP network socket that was suitable for web traffic, since the engine primarily functions with UDP sockets for multiplayer use. This was achieved with a feature initially put in the Source engine for server management in the Left 4 Dead games. From there, the game engine just had to be set up to reply to HTTP requests on that socket with the proper responses a visiting browser expects. If the game engine responds to a browser’s connection request with a bunch of HTML, that’s what the browser will display. Bam! You’ve got a web server running in Portal 2.

From there, [PortalRunner] went further, setting things up so that the status of in-game objects effects the HTML served up to visiting web browsers. Move objects in the game, and the served web page changes. It’s pretty fun, and the complexity and features [PortalRunner] implements only get more advanced from there. When he gets into stacking companion cubes to write HTML in visual form, you’ll want to applaud the Minecraftian glory of it all.

The devil is really in the details on this one, and it’s a great watch. In reality, making Portal 2 into a simple web server is far easier than you might have thought possible. Valve’s physics masterpiece really is popular with hackers; we see it popping up around here all the time. Video after the break.

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Building A Wireless Motorized Fader For Lighting Control

May 31, 2025 by 2 Comments

Motorized faders are very cool, and you can find them in everything from expensive mixing desks to high-end video editing decks. If you want to build your own wireless motorized fader controls for your own projects, you might like this project from [Ian Peterson].

Faders are useful controls, but they’re usually very one-way devices—you set them to what you want, and that’s it. However, motorized faders are a little fancier. You can move them yourself, or they can be moved under the command of other hardware or software—making a control change automatically that is still visible to the human in front of the control panel.

[Ian Peterson] built his OSCillator motorized fader for his work with lighting consoles in theater contexts. Its name references the Open Sound Control (OSC) platform which is commonly used across various lighting consoles. His build relies on an ESP32 to run the show, which communicates with other lighting hardware via WiFi. The microcontroller is responsible for reading the position of the fader and built-in button, and sending the relevant commands to other lighting devices on the network. At the same time, it must also listen to commands from lighting consoles on the network and update the motorized fader’s position in turn if the relevant control it’s mapped to has been changed elsewhere.

If you’re working in theater or film and you’re wanting to control lighting cues wirelessly, a tool like this can really come in handy. We don’t see a lot of motorized faders in DIY projects, but they pop up now and then.

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