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One of the great mysteries of childhood is how an Etch-a-sketch works.

It seems like a mystical creation that lets your imagination run wild.

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Leave it to a pair of Youtubers – Grant Thompson, better known as “The King of Random”, and What’s Inside – to chop one up and explain the magic going on inside.

It’s an eight minute video, but the good stuff starts at the three minute mark when they bust out the Sawzall and go to work.

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An Etch-A-Sketch is basically a plotter. The inside surface of the glass screen is coated with aluminium powder, which is then scraped off by a movable stylus, leaving a dark line on the light gray screen. The stylus is controlled by the two large knobs, one of which moves it vertically and the other horizontally. Turning both knobs simultaneously makes diagonal lines. To erase the picture, the user turns the toy upside down and shakes it. Doing this causes polystyrene beads to smooth out and re-coat the inside surface of the screen with aluminum powder. The “black” line merely exposes the darkness inside the toy. Filling in large “black” areas allows enough light through to expose parts of the interior.

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So they found what you’d expect. A mess of aluminum powder and the same basic mechanics that have been entertaining kids for more than 50 years.

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