According to Ohio Arts, the powder inside an Etch A Sketch is not dangerous, but it sure would make a mess if you broke one open.
It’s aluminum that’s ground fine so it will stick to everything it touches, with some small plastic beads added to agitate the powder and keep it from clumping together.
How does it draw? Each knob controls nylon strings that move a cone-shaped brass stylus.
The stylus removes a thin line of powder from the inside of the glass, revealing the darkness of the inner compartment.
If you scrape away enough in a systematic way, you can actually see what the strings and stylus look like.
To make it difficult to damage, the glass is covered with a thin layer of plastic.