Behringer’s 2001 FCB1010 “MIDI Foot Controller” is a curious device. Ten assignable control pedals and expression pedals let you do — well, anything that you can do using MIDI, from controlling instruments, to lighting and effects, to automation.

But what if it could do even more? This was the question the PJRC forum user Expensive Notes asked themselves as they hatched a plan to gut and replace the internals with a Teensy 4.1 and Teensy Audio Adaptor Board.

The project’s forum thread and accompanying videos detail its evolution into a mono synth, drum machine, and sequencer with SD storage. More detail and generously-documented code can be found in the project’s GitHub repository.