Hi there,  I'm not sure if anything was posted about this yet, but
I just came across a short documentary clip about the Stalacpipe Organ
in the Luray Caverns near Shenandoah National Park in Virginia, USA.

While it is wired to a four-manual console, the clip also showed the
"organ" being operated alternatively by a "barrel".  To not have to
re-pin large barrels, they only have one barrel, but they slip-cover
it with a plastic film that has the "knobs" on them.  During the many
years since it was built, they also added (of course!) an electronic
control (still using old 3.5" floppy disks) to play the instrument.

I found a few web pages for the organ at:

  http://www.oddmusic.com/gallery/om25450.html 
  http://en.wikipedia.org/wiki/The_Great_Stalacpipe_Organ 

and various YouTube clips when searching for "stalacpipe"

Musically,
I. Krause
Surrey, British Columbia, Canada