This project has evolved so much since December last year… I have been completely out of the forum since then but I have been working on it and on many other things too.
I have developed 3 base platforms to build modules on top of them, I call them Motherboard6, Motherboard9 and Motherboard12.
I have reworked this synth, renamed it to just Synth, it is based on Motherboard6, so it has 6 controls now.
Here is a demo, I play from the laptop, sending midi via USB:
I have built also other modules, Psyc03 (an acid percussive synth), DS9 (a drum synth), Byte (a drum sequencer), Cycle (a note sequencer), and Drone (which is obvious).
They all communicate via midi over jacks from the back.
I am very close to be able to jam properly with my modules now, here is a recent test of 4 modules together: