For the San Francisco Stupid Hackathon, I wrote a program that would convert your keystrokes and mouse clicks into random tones. It was inspired by nbeep, and I wrote it in a few hours having absolutely no idea what I was doing beforehand. It turns out, macOS programming is a lot like iOS. Neat!
It can be installed with:
brew cask install philihp/casket/r2
Postmortem: What did I learn? It's actually very difficult to build something like this. Even my own brain was trying to trick me into making something useful.