The Scout is an Open Source, Arduino-compatible, 3D-printed, 17 key, monophonic square wave synthesizer keyboard from Oskitone! Assembly takes about 45 minutes using basic through-hole soldering.
When it's done, connect an FTDI serial cable (not included) to reprogram it with the Arduino IDE. You can even print the non-electronic parts yourself if you have a 3D printer.
Controls: keys, volume, on/off switch
IO: built-in amp and speaker, headphone line out, UART header
Power: 3 AAA batteries (not included)Assembly and 3D-printing guide: https://oskitone.github.io/scout/