Northern California, USA
I play guitar and needed a drummer to keep the beat during my gigs. I've played with drummers in the past. But I wanted to continue playing solo. Of course, there are many electronic drum machines out there -- but I wanted something acoustic.
At the core of the unit is an Arduino Uno driving solenoids. The Arduino just listens for incoming MIDI notes from an external sequencer and triggers the corresponding solenoid. I installed a MIDI shield on the Arduino and connected it to a Yamaha MIDI Bluetooth controller.
This lets me design and deploy patterns from any Bluetooth MIDI enabled app. For gigs, I just put my iPad on a music stand and control the unit from that.
Of course, I didn't want to reach over to the iPad during a song to turn patterns on and off. So, I modified an old volume pedal and connected it to the Arduino. This lets me fade the unit in and out at will.