The Grind Customs FX SuperNature PCB is a clone of a 1976 Coloursound Jumbo Tonebender at its finest.
It has the girth of a Muff (shares quite a bit of the same topology), but with the fizz of the older fuzzes like the MkII.
This PCB was actually populated by Juansolo and sent to me to play with. I could not put it down! It sounds awesome with my Gibson SG ran into my Bassman 135 2X15 cab… earth shattering.
Gut shot: Used the Grind Customs Lumen optical bypass.