I have no experience with these, but when looked for possible Fuzz pedals to build for a mate of mine who loves nasty and lo fi fuzz I came across Devi Ever Disaster Fuzz, Death by Audio Supersonic Fuzz Gun, Death by Audio Harmonic Transformer, Dwarfcraft Great Destroyer and Devi Ever Legends of Fuzz.
I picked these out of a big list of schematics looking for lo fi nastyness and just out of controll crazyness.
I have not yet build any of these though cause enclousures cost money xD
Also great is the Zvex Fuzz Factory, especially if you have someone build a clone for which includes a tonestack (which I think should be post circuit). The stack allows it to even be a mean metal machine when it would normally not work since you can cut the bass. Fuzz is great but usually better for single notes than chords, exept if you cut the bass.