From Copper Foil to Custom PCB: Building a DIY Touch Piano with Sridhar Rajagopal

What does it take to turn a strip of copper foil tape into a full-fledged musical instrument? For Sridhar Rajagopal, the maker behind ProtoStax and the Dr. Wattson Energy Monitoring Board, the answer unfolded over years of iteration, curiosity, and a genuine love for both music and hardware.

In his Maker Faire Bay Area 2025 talk, Sridhar walks us through the evolution of his DIY capacitive touch piano synthesizer and MIDI keyboard, from a scrappy first prototype to a polished, feature-rich instrument built on a custom PCB. It’s a project that started simply: copper foil keys, an Arduino, and a handful of jumper wires. From there, it grew into a compact 3-octave touch piano with addressable RGB LEDs, an onboard amplifier, and full USB MIDI support.

Whether you’re a maker curious about cap