Loudness and Distortion....and clean off course with the on/off. With the dist at zero the Loudness is preamp gain of what? that could over drive a tube preamp nicely too.
The switch is for symmetrical clipping (which is the stock design hence the S) and Asymmetrical clipping (mod). The stock setting is just a couple of zenner diodes in parralel and the mod is a 1n4001 and 5mm LED in parallel.
Enclosure was powder coated at home, then I had a friend screen print it, then I put clear powder over that at home.
The result is a very durable finish and powder coating takes around 2 hours between both coats from start to finish (based on both cure time and time it takes to cool after it's baked on).
All in the pedal was around $70 to build including finish (although I admit if you don't know a dude who can hook you up with screen printing the price would probably go up, it was a learning experience for both of us. He had never tried screen printing a pedal before). Outsourcing powder coating is pretty pricey from what I hear as well.