Bill Clark wrote in 100630 MMDigest, "Where can I buy or get
plans to make a beater mechanism?"

Player-Care sells just the book for you!  Visit
http://www.player-care.com/orchestrion.html  for "The Orchestrion
Builder's Manual and Pneumatics Handbook", by Craig Brougher.
Chapter 12, Designing and Building Percussion Instruments, has
several pages of discussion and sketches and includes a versatile
double-beater reiterating snare drum mechanism that runs on vacuum.

Or maybe you'd like to make an electric reiterating snare drum
beater, since your MIDI-controlled band organ already incorporates
electric bell strikers.  Check at eBay auction for an open gong
electric door bell; for example,
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160450126255 

Robbie Rhodes
Etiwanda, California