Building computer-controlled Pipe Organs is very much easier than building trackers.
You don't need complex machanical parts, but only magnets which are directly linked to a
direct power interface. This power interface is linked to a PC.

FOR A COMPUTER CONTROLLED PIPE ORGAN:
The only parts you need are:
 

Item	Availability	Approx. Price	Remarks
Pump	Available by different Companies Contact P. Leray	See picture	same price for trackers
Regulator	Can be built with wood parts	price of wood	see description
Body (Sommier)	very easy with electro-magnets equipment	price of wood	Largely less expensive than for trackers
Magnets	Many magnet builder Companies Contact P. Leray	Various prices depending on  the supplyer	Less by quantities; Car magnets could also be adapted
Pipes	More difficult, mainly for little pipes	very different prices	Ancient pipes also available
Keyboards	Midi keyboards Contact P. Leray	from 200 to 400 $ each	Can be added without limitations
Hardware (Power Interface  Comnbinator)	Combinator description	Approx equal to 1-2 stops
Software	Software description	Bundled with hardware (Standard version)