P. J. Lascano wrote [181207 MMDigest], "There is, in my opinion,
not much to learn by pinning a barrel of a cylinder... "

I would tend to disagree.  There is a lot of current information
available on the construction of MIDI devices, particularly small
organs.  There is very little readily available information on
barrel pinning technology.

It is easy to use organ technology since you will have an air
supply if you are using pipes.

Mike Knudsen covered the basics in his Carousel Organ magazine
articles "Build a MIDI Interface for the Raffin Crank Organ" at
http://www.wallace-venable.name/mechanical-music/MIDI_Systems/ 
and which can be accessed as

http://www.wallace-venable.name/mechanical-music/MIDI_Systems/Build%20a%20MIDI%20Interface%20for%20the%20Raffin%20Crank%20Organ_Mike%20Knudsen_%2318-19-%20pneumatic%20tracker%20J-Omega.pdf 

You will also need to gather some up-to-date information on MIDI file readers and current output boards.

Wallace Venable