Oh snap- this is awesome, well done! As I was going through this post I was thinking how awesome it would be to have a little robot trap set (snare, base drum, tom-toms, symbols, etc.) drummer that plays along to my pop music while sitting on my desk to give me a little show whenever I need to smile. Or maybe a little bongo player.

Super fun!

I've been thinking about something similar for a long time, although fully chromatic, about 4 octaves. Either percussive, with reeds, or flute organ pipes. Where I always get hung up is the cost of all the solenoids or valves. There's some amazing projects on youtube but they must have cost hundreds.

Has anyone done something similar with more notes?

I love that the design is based on a Cray II [0]! I recently saw the original supercomputer in Paris.

I can't quite see why this would need a Arduino Opta, over a regular Arduino Nano (maybe with a multiplexer?) - is it because the solenoids are 24V?

https://en.wikipedia.org/wiki/Cray-2

I really wanted for it to be a robotic tongue drumming all the ambient hits.