My DIY Modular Synthesizer, 3 oscillators, 1 dual gate delay, 3 ADSR modules, and a Moog Ladder Filter clone. Everything was handmade aside from the case brackets, the Pittsburg lifeforms modules, and
Further With Filters
CGS bandpass filter - Synth DIY Wiki
AUDIODiWHY : Korg MS20 Filter--the Why in AudioDIWHY.....