The micro-TS Kit
The Micro-TS is a keyfob sized, 61x41mm touch synthesizer.
Probably the smallest playable and tweakable synth in the world.
It runs on 3V so a CR2016 button cell works just fine.
The analog knobs have a trim potentiometer footprint.
Output is a 3.5mm stereo headphone jack.
It has CV/Gate outputs as pads on the PCB edge.
This is a PCB + Chip DIY kit.