The Magnetic Pen Theory
Not hard to do. Use a very small tipped magnet and you can draw on it like it was an artists PC Drawing Tablet. Now if it was actually honest to Doug drawn using the actual vertical and horizontal knobs then that would be butt impressive. Perhaps a video of the act (sped up of course) would make this amazing. But its a pic so conversely...BURIED!
The Higher Than Normal Quality Etch-a-Sketch Theory
Last time I tried an etchasketch, you couldn't do angles on it without it looking like stairs. Either this 'travel etchasketch' is of much, much higher quality (doubtful), or this is faked.
The Silver Paper Theory
I call fake, how easy would it be to open this up and slip a silver sheet of paper in place of the screen and drawing in pencil which is essentially what the lines on etch a sketch look like.
Of course, they can't all be right. Either it was a magnetic pen, a super-special high quality Etch-a-Sketch, or it was the silver paper slipped under the glass. Which theory is correct? I'll let them fight it out amongst themselves. But when you guys do figure it out, please let me know. I'm dying to find out how I do these things!