This is something I made in anticipation of a similarly constructed robot controller for Robomancy.com. The keys were designed in Inkscape and printed onto cotton letterhead, then painted over with Bare Conductive paint (you could just paint the keys; I am not a terribly good painter, so I like to design on and print from a computer). I connected them to MaKey MaKey, which lets you turn pretty much anything that conducts even small amounts of electricity, into a button or switch that is interpreted as a keyboard or mouse action on a computer. I wrote a Processing sketch that reads each key and displays a corresponding color and plays a corresponding note. The black, shungite pyramid is conductive and connected to the ground part of the circuit, so when I touch the pyramid (with my right hand, in the video) and also one of the keys, I pull some of the electricity through my body to ground — enough for MaKey MaKey to recognize which connection I have altered, and activate the appropriate output.
(I have only six of the seven keys wired in the demo video, because more would have required the addition of a mouse action, and I just wanted to keep it simpler than that, but it is possible to use all seven.)
The correspondences I used are from Paul Foster Cases‘s Correlation of Sound and Color (you can find PDF copies online); there are others. If you are interested in his sources, Alison Deadman wrote an excellent article about them: “Letter, Musical Pitch, and Color in the Work of Paul Foster Case” (links to PDF). Dr. Deadman teaches music history and Alexander Technique at East Tennessee State University.
I have imagined many uses for this technology; a variety of ritual interactions. E.g., a conductive talisman that “charges” the magician when she completes a circuit by touching the talisman with one hand and an earthed device (metal stang?) with her other — perhaps triggering lights or video, music or other sound. Or printed/painted psionic devices. Etc. Feel free to share your own ideas in the comments.