This layout is a modded version of the Madbean's Boomstick project, which is his take on the Distortron (which already has a layout here).
http://www.madbeanpedals.com/projects/Boomstick/docs/Boomstick.pdfI'm posting this as an alternative layout with my own personal mods, but if you've built a Distortron or Box of Rock, this may be superfluous for you.
The mods I added are as follows:
(1) Put a 1uF cap across the C5K gain pot. This enhances the mids and upper frequencies and reduces the low end gain on the first MOSFET stage, which made the original sound a little too boomy to my ears.
(2) I replaced the simple source short-to-ground boost with a 330 ohm source resistor and 2.2 uF cap in parallel. Sounded a little better to me.
(3) I modded the tone stack using the Duncan Tone Stack Calculator as my guide. Trebles may be a bit too bright for some - if so you can revert back to original cap and resistor values.
I also replaced the input 100 nF cap with a 33 nF cap, but I think that may be unnecessary so I left the original in the layout.
Have fun and let me know if there are any problems with the layout (I've built this already)!