The Tiny TS is a credit card sized (100x65mm) fully open-sourced synthesizer with a 1-octave capacitive touch keyboard. It has Audio/CV/Gate outputs and 6 synth parameter dials.
The DIY project site is found here:
These are the 3D STL-files for printing the casing.
There is also a PDF-file included for the panel graphics.
Fancy building it?
The PCB+Chip kit can be found here: