Here’s a work in progress video of my home-made musical instrument, the Nickelphone.
It’s a coin-based music keyboard. 15 nickels and 10 pennies act as touch sensors on a traditional 25-key piano-style layout. It currently emits one tone at a time through a little piezo buzzer, but it will eventually emit MIDI signals so it can drive a full synthesizer (like FL Studio). Based on an ATmega644 microcontroller and coded in Arduino with the CapacitiveSensor library for touch sensing.
I’ll do a full write-up here when it’s done.