Envelope generators, oscillators, ring mods...build a synth !

[Dragonfly]

I;'m sure you "synth guys" know this site, but the guitar pedal guys might not...

http://www.digisound80.co.uk/digisound/modules/80-1/80-1.htm

Lots of great old ETI synth module stuff here... (can be converted for guitar usage...)

[frequencycentral]

I believe Digisound 80 modules are based around Curtis chips, which are expensive and can be difficult to source.

There are better options out there.............I have a pile of synth schematics!

[Mark Hammer]

Rick is correct.  You'd need a heap of Curtis chips to make this thing.  Given the going price, it would be cheaper to buy a Roland guitar synth.

Do take a look at the stuff at the Music From Outer Space site, though.  That uses currently available (and affordable) chips.  Plus, Ray Wilson is a funny guy.