years ago i've build a midi pedal custom board for a friend of mine, Mauro.
Just in that weeks, i take time to release it as open source.
A few improvements can be done, like using a matrix input instead of the shift registers, use an ATmega instead of the ATTiny, also changes to the code, make it more clear, allow multipress (at present two button pressed the same time does not works), even if the first idea was to use foot, and press two button at time using foot is difficult
Anyway, the project as proposed works, that's the project link:
http://davidegironi.blogspot.it/2014/10 ... ntrol.html
Hope it helps.
Note: that is not on sell, it's open source, you can build your own