1 simple on/off switch/button/knob/etc. PSU \+12V, -12V and ground needed, probably up to 1amp - maybe not as efficient as a vendor? VCF MK's Diode Ladder VCF Kassutronic's KS-20 VCA MK's VCA Everything by Hagiwo (quantizer, filters, noisemakers, etc) MIDI-to-CV, either over USB or directly over 5-pin DIN (with optoisolator) What we build next? Pretty confident we do know we need a flat but not limited to software source code, even though third parties to this height controls label depth.