Stanley Lunetta’s CMOS-based instrument designs have earned a strong following among the synth-diy crowd – and for good reason. The circuits can be relatively simple and the resulting sounds quite interesting. Bchris1776 shares details about his above-seen super-patchable unit –

This Lunetta is built primarily from 4000 series CMOS integrated circuits with inputs and outputs taken to front panel jacks to be patched to other sections. This Lunetta uses counters, shift registers, XOR gates and 40106 schmidt trigger clocks and oscillators.
There are those who can make some great music with these – however I’m not one of them :)
There was no great thought put into this patch – I just plugged and played as I went. As such, every audio result was a surprise as I changed patch locations and clock speeds. I think that’s half the fun of these circuits.

Head over to the Electro-music forums for more project info and users’ builds.