Member 12afael here has the complete project (I think). Perhaps if you search a little. I think he has a pdf with a PCB and schematic etc. IIRC there was everything you need. A member livingnote here can perhaps help you with PCB etching if you aren't making it yourself.
However, I'm not so sure about amaziness of the pedal. Perhaps mine is a dud, but I doubt that... However, everybody is used to work with sansamps, so if you walk into a studio as a session player, you must have one these days..
Edit: the project file is here
http://sites.google.com/site/plexilandia/
http://sites.google.com/site/plexilandia/tech12bassdriver.zip
Perhaps you could try to contact 12afael and ask him if he has higher-resolution pcb artwork available.