The NovaDrone from Casper Electronics is an open source, analog experimental sound a light synth. It's currently available as a pre-assembled board, PCB only, or PCB and kit in both single and double versions. Prices start at around $100 for the full kit, with a board only and a parts also available.
Here's the blurb
Each channel has the following features:
-TONE pitch coarse tune 24Hz to 750Hz
-TONE pitch fine tune
-LFO rate .008 Hz (around 1 cycle every 2 minutes) to 750Hz
- ext sync 3
-LFO rate modulation
-TONE square wave
-TONE triangle wave
-LFO square wave
-LFO triangle wave
-PWM square wave
-High current LED out for off board LEDs.
Affordable workstation type keyboard