Here's what you need:

– 1N4001 diodes [x2] (though Dan from T1M said any diode will work when I emailed him about it)

– Stereo ¼” jack

– SPST momentary footswitch [x3]

– Enclosure (and a drill if you don't already have one)

And obviously a soldering iron + hook up wire.

Here is a great/easy to understand tutorial:

http://www.youtube.com/watch?v=QHAX15niYBM