NOTE: if you are thinking about building one of these, see my newest addition first based on the 'Little Gem' amplifier, using a few more parts. It sounds much better.
Step 1: Parts List / Wiring Diagram
Enclosure: I used an old surround sound speaker as my enclosure. You could make this unit into a box and use as a 'head' for speakers in mini-cabinets too.
9V Battery Clip
Input / Output Jacks 1/4 Mono
SPST Switch OR Dip Switch w/ 5 settings
PCB / Board material
8 Pin IC socket (optional)
[optional - for multiple distortion modes]
2.2 uF capacitor
+ higher cap values = heavier distortion