Believe in magic.

In the early 50's a French inventor and tinkerer, Andre Cassagnes, came up with what was eventually to be the Etch a Sketch. A stylus, controlled by joysticks, scraped it over an aluminum powdered sheet of glass. The contraption was housed in a box and originally called the Telecran. "Ecran" is French for screen. The shape mimicked the other insanely popular screen emerging in households at the time, televison, hence Telecran.

Anyway, the device made its way to the 1959 International Toy Exhibition in Nuremburg where Ohio Art Toy Company president Henry Winzeler first saw it and had to have it in America. The original still had the joysticks so when Winzeler looked at it he decided to replace these with 2 knobs. This had advantages in that the toy was immediately more intuitive to use and it looked a lot more like a TV, which was great marketing.

If you have the patience and want to see the inside of one, simply draw a whole lot of horizontal lines. In essence you will remove all the aluminum powder from the glass and then you can peer into the case through a nice clean window.