How does an Etch-a-Sketch work?
An Etch-a-Sketch is actually a pretty amazing device! It is essentially a manually operated plotter with a built-in erasing system. Anyone who has used an Etch-a-Sketch before will recognize the familiar red plastic toy with the glass drawing window (now also available in other fashion colors): Etch-a-Sketch Image Gallery It is not easy, but you can get inside by removing the outer case and the glass: What you find inside is a stylus mounted on a pair of orthogonal rails. These rails move when you turn the knobs. Also inside is a mixture of extremely fine aluminum powder and beads. The beads help the powder to flow evenly. When you turn the Etch-a-Sketch upside down and shake, it coats the inside face of the glass with aluminum powder: An obvious question, prior to playing with this powder, i
