Creating the EtchASketch was very easy, as I have a complete understanding of the process of this device from my childhood. I immediately whipped together two 10k potentiometers to act as the left and right dials. On the Arduino coding side, I just set it up to read the analog data from both dials. On the Processing coding side, I had it use this information to control the x and y location of a small ellipse that would act as the brush.
For the music machine, I had Processing just record the vertical location of the mouse and send it to Arduino, which then translated that information into a tone.
