Anyone here who dabbles in synthDIY as well as guitar effects DIY knows MFOS and Ray Wilson's work. He developed the SubCommander, a super versatile guitar synth in the vein of the EHX Micro Synth:
http://www.musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&VPW=1670&VPH=819This project looks huge, the schematic spans more than 6 pages... but I thought again I'd share for the sake of knowledge and in case anyone was working on their own project and wanted to incorporate any of these techniques and circuits into their designs.
Ray's got a ton of other great projects on his site, mostly synth related but there are a few other guitar- centric projects and they're all pretty amazing.