Rainbow Theremin is a project that tracks any magenta colored object with the user's webcam for X/Y/X coordinates, and then converts those X/Y/Z coordinates into a Theremin’s amplitude and frequency (as well as a paintbrush's size and color). If you’ve played around with it a bit, you might have noticed the fatal flaw in this idea - painting a beautiful picture makes terrible theremin music, and making good theremin music makes for horrible paintings. Even so, this is a fun little toy that I thought I’d share. I wrote it while doing a fellowship at the Recurse Center with Node, Express, and p5.js, a Javascript Processing library.
You can check out the GitHub repository for it here, and you can see a live demo of it here - note that it requires a webcam and likely will not work on older browsers or on mobile.