Caleb Coppock's "Graphite Sequencer" is an analog drum machine of sorts that works through simple electrical conductance. Two wires scrape along the surface of a spinning paper disk with graphite shapes scrawled across them (graphite is a conductive material) so that when they pass over the shapes, they generate tones. The resulting sound is then amplified and played back through the device's speaker system. Coppock has customized the device so that when the graphite line is thick, allowing more current to pass, the pitch of the resulting tone changes to a lower one. This is in contrast to a thinner line, which creates a very high-pitched tone on contact. Although the resulting sounds are anything but musically appealing, the ability to hand-draw your own beats is a nice and simple way of creating audible results from physical media. The video on the project's website illustrates how this works although the resulting sounds are a bit difficult to stomach.
Jonah Brucker-Cohen