Even just the plain etch-a-sketch using motion sensing is cool enough.

I suppose this might have been done already?

I did NOT know the motion sensors on my phone were THIS precise, that’s surprising

change paint brush size -> whistle

change color -> put finger in front if camera

make drum sound -> tap side of phone

Is there a reliable way to trigger percussion?

tap the side of the phone, it responds to accelerometer sensor.

Tapped very hard, never worked once. Using android on pixel phone.

A digital theremin! Very fun.

which reminds me of building breadboard RF sensors (using fixed caps with variable for calibrating parasitic capacitance) and since these are just oscillators you can calibrate a beat frequency (heterodyne mix) in audible range that has the theremin timbre of a squarish sine wave that you can plug straight to a speaker

It seems to make the user dance, would fun to see video of people using it for the first time. haha