For everyone interested in do-it-yourself (DIY) MIDI control, see
http://www.ucapps.de/  especially the MBHP (MIDIBox Hardware Project).

Thorsten has released the MIOS (MIDI Operating System) that is not only
free, but is open source and has hooks for users to add their own
controller code.  See the MMD article by Willy van der Reijden about
how he used the earlier version of the DIY MIDI controller on his
orchestrion: http://mmd.foxtail.com/Tech/mvdReijden.html

Mickey Sadler
Dublin, Ohio