From there, your next friend (or a random stranger) can step in and repeat the process. Up to four people can add parts to the song, and when it's ready, you just hit "save and upload," to create an .mp3 file and store it on a special website.

To build the piano, the team used 1970's era Bose speakers, electromagnetic bar pickups and clever programming on the Pi. They also had to saw and drill the piano extensively to get everything to fit. It's now installed in a mall food court in Lancaster, Pennsylvania, and hundreds of users have already added short songs. Yes, there's a lot of Chopsticks and random plinking, but there are a few decent efforts as well.