The Werkstatt-Ø1 is an educational tool and a compact analog synthesizer from Moog.
It was designed to give people a thorough understanding of how synthesizers work.
There is only one oscillator with a frequency control allowing tuning from 8Hz up to 16kHz, and a 4-pole ladder filter with cutoff and resonance control.
[1] To assemble the Werkstatt-Ø1 you have to screw the printed circuit onto a metal chassis.