My best guess is that he just wired in a super high gain circuit in (possibly with a delay) and that just makes feedback naturally. I would just pm his YouTube.
Quote by Most_Triumphant
Depends, I don't know what pickups go good with plywood. EMGs will make it sound like every other EMG guitar though.

Quote by JazzMunkeyy
it needs a silver flakes
and sara underwood
Look up the Big Muff Feedback Loop mod. I'm willing to bet that the circuit is as similar as the casing they put the pedal in.