A library and a CLI tool for generating and decoding a custom matrix barcode similar to a QR code.
An attiny85 development board with a builtin 3v3 output and power and general purpose LEDs. Comes with USB-A.
No fuss Linear Programming solver with a friendly API. Uses the simplex algorithm.
Uses some Unicode magic combined with VT100 escape sequences to display an image (or a video) in the terminal. The larger the terminal window, the better the resolution ;)
Custom design of a single-key (mechanical, of course) USB keyboard powered by an attiny85. Works great as a quick lock-screen button.
An immersive simulation of a ship traveling through space done using only 2D canvas to avoid having to use WebGL. Source here.