The other day I had a lesson for the series "month of science": music - day: conductive ink.
You take some conductive ink, paint some object with it, connect to an arduino, turn them into musical instruments. I drew a keyboard on the wall and made it play, kids love that kind of stuff.
- https://www.youtube.com/watch?v=qtDZ3fYyUN0
EDIT: few more
- https://www.reddit.com/r/synthdiy/
- https://create.arduino.cc/projecthub/pr ... tags/music
- https://www.makeuseof.com/tag/arduino-midi-controllers/