The Cheapstick is a Proof of Concept for a research publication by Alexander Jensenius, Rodolphe Koehly and M. Wanderley published as a conference paper ( CMMR, Pisa, Italy, 2005 ).
The paper presented custom methods for hacking a game-pad and plug sensors onto it, an then used the inputs signals through the HID protocol used for game-pads signal acquisition and included in most OS systems.
Software like MaxMSP or Pure Data possess[ HID] objects to get input sensors signal data and map them for musical or graphic applications.
This makes a very low cost and easy to program micro-controller if you get a second hand Game-pad.
The same concept can also be used to hack game-pads from you game consoles.
Using paper sensors you can build for position or flexion sensors of the size of your will, thus being able to reproduce any type of music instruments or video games controllers.
The Cheapstick was the first of its kind, and simply consisted in One square force sensor to trigger a sound and one position sensor to select the sound pitch or other sound spec.