Design News reports that as a fun demo of application possibilities
for pneumatics, Clippard Instrument Laboratory, Inc., has created
a real "air guitar", using 62 small pneumatic cylinders and valves
to play a real guitar:

  http://www.designnews.com/author.asp?section_id=1395&doc_id=239327 

A direct link to a video of it, in action:

  http://www.youtube.com/watch?v=8pdjxWmwMdU 

In my opinion it's a bit "clacky" (a "beat box" "clap" cylinder was
deliberately added to make that clack, probably to cover the sound
and hiss of the other actuators).

I'd probably be tempted to just add a few more rubber pads to the
actuators, and take the air vent further away from the instrument,
so you'd only hear pure music.  But it's a fun, modern example of
mechanical music.  I especially like the use of clear acrylic for
mounting, and multi-color LED edge lighting.

Keith McClary

 [ The inventor, Robert Clippanrd, describes the instrument at
 [ http://www.youtube.com/watch?feature=endscreen&v=XZyq4Hz7EKU&NR=1 
 [ -- Robbie