I started with a simple wooden keepsake box I bought for $0.99 at the local thrift store.
Next, I removed the lid and hinges from the box, and saved the lid to close the bottom of the pedal once I was done building the insides. Nothing too complicated yet.
(Missing a few pictures here - I got too excited about the build and forgot to photograph the in-between stages)
The only parts I used for this project were four (4) 1/4" input jacks, and an SPDT switch (Single Pole, Double Throw). Before installing them, I used copper shielding tape to insulate the insides of my enclosure. Using a metal enclosure would make this step unnecessary.
I used some orange spraypaint to cover the enclosure, and made paper stencils for the symbols on top. If you want to go low-fi, a Sharpie would work equally well, I think.
The finished product: a fully functional, and actually pretty useful pedal (and it's my favorite color!)