This synthesizer relies solely on an FPGA for key detection and sound synthesis. [Chris] and [Joe] built it for their final project at Cornell. The hardware implementation includes velocity sensing for the keys. While at rest, each key contacts a strip of copper foil. A matching strip of foil contacts the key when it is depressed. The velocity data is extrapolated by detecting when a key leaves the rest state and arrives at the depressed state. Sound synthesis is handled in hardware using the Karplus-Strong string synthesis method.  If you want to hear what it sounds like, they’ve posted a video (MP4) that shows off the creation. It sounds like an electric piano to us, so mission accomplished.