Making progress! Because of the start of a new semester at my university, I tried to finish a first version of the edusynth. And, also to my own amazement, I did! Here’s a first 3d brd view of the eagle file:
Dual VCO, VCF and VCA. Dual ADSR and a number of OPS (CV, mix and split). Board are ready according to pcbway – I’m waiting for delivery… First try outs to follow. Also, the edusynth is full open source / open hardware thus schematics and code also underway.