Inspired by the theremin, Jay Silver and Eric Rosenbaum at the MIT Media Lab have created a small sound circuit that can be attached to a pencil of paintbrush and will play a variable pitch when the drawing or wet paint is touched and the pitch can actually be controlled by your finger's position on the paper.
This little device can definitely spark some new ideas in your sketching! Their video shows some of the creative and playful results from having a theremin on your drawing stick.
