Dear Marc Elbasani,  I read your post today about building a band
organ.  I too have run this idea through my brain many times.  Due 
to lack of space I have had to give up the dream,  well sort of!

I read what you are trying to do so here is a suggestion.  Build the
MIDI interface first and get it to activate lights or LEDs.  Then build
your air, valve and actuator section.  At this point I would use the
unit to play an accordion or chord organ.  Leave the accordion intact,
let the actuators press the keys.  Once you got to this point adding
pipes and other devices would be a snap.  Good Luck!

John Conrad Kleinbauer