Alan Pell offers drum beaters for snare (reiterating) and bass
drums.  They each work on pressure, and the MIDI signal controls
solenoid [valves] which open and close the air supply.  There are
many components available for the home builder on his web site.

Bob Yorburg, New York (builder and carver of the Wurlitzer 165
facade that graced the cover of the recent MBSI Journal).