At hackaday a DIY synth was lauded, and I must say it sounds great and the device looks great as well, uhm at least on the outside. Wait for the last bit of the video where you can see its innards (from 10m05 on). I bet some of you will be as surprised as I was.
I’ve been watching this video many times. It is however a bit sad that we don’t have much references to the various parts. Even if the modules are homebrewed some little info had been fine.
But another video of a similar machine was thrown in my face by Youtube’s algorythms:
https://www.youtube.com/watch?v=pvwY2c6shvQ
Here are sources of the module cores given (cheap stuff 
).