Mykle Hansen designed this open hardware add-on board that lets you play your Pocket Operator drum machine like a maraca:
Pocket Integrator is a magical, musical add-on board for Teenage Engineering’s Pocket Operator drum machines. Using a MEMS accelerometer, it lets you play drum patterns and synthesizers by tapping and shaking, just like a handheld percussion instrument. Play your Pocket Operator like a drum!
Tap to set the tempo and downbeat. Keep tapping as long as you like. When you stop, it’ll hold the beat wherever you set it. It’s as easy as clapping your hands! (In fact, it’s like using your hands to clap another pair of hands that magically keep clapping after you stop clapping your hands.)