Made a Sparkle Motion! I remember there was an issue with someone a while ago selling clones of this circuit, I don't have any plans to do that. Who would want this impractical, bordering-on-ugly box anyway? Well, I do, so that's why it exists.
Built pretty much 1:1, breadboarded it first and slightly skewed some resistor/pot values (IN is 250kB). Russian NOS MP38 transistor and big switch, housed in a pre-powdercoated enclosure which I painted with this spillover design from a computer mock-up. I dunno, it's awkward and unnerving to me hand painting enclosures, if I do it again I'll make some kind of recessed rig to hold the box and support my arms.
The sound - Now I've never tried a real SparkleMo, but from the demos I've heard this one doesn't get fuzzy except when pushed. I think these MP38 trannies are just lower gain than what's in the OG. It remains to run it through a suitably dirty amp, but the treble boost is there in spades. Bias control turned out to be pretty subtle. The full range mode is heavy. Excited to try it with different instruments/amps.