If you were a child, had a child, or knew a child anytime in the last 60 years, then you’re familiar with the Etch A Sketch. The magical toy lets you draw by turning a pair of knobs like a manual plotter. But, while an Etch A Sketch is great fun, it’s also really difficult to create anything resembling art. Art is for suckers anyway, so you might as well cheat and use a Raspberry Pi to do the heavy lifting for you.
Sunny Balasubramanian’s build tosses all of that manual drawing nonsense out the window, and replaces it with good ol’ fashioned CNC (computer numerical control). Two small stepper motors are attached to the Etch A Sketch knob shafts, which move the drawing mechanism in the X and Y axes. The stepper motors are connected to the Raspberry Pi’s GPIO pins through stepper drivers, which are necessary for controlling any stepper motor.
With the mechanical setup out of the way, it was time for the real challenge of plotting a photo. We all know that the trickiest part of drawing with an Etch A Sketch is the fact that the line is continuous, which is a major hurdle on the way to creating a decent picture. This process starts by taking a photo and passing it through an edge-detection filter. The largest “network” of connected pixels is then kept, and other elements are discarded. The remaining pixels are converted into a continuous path which can be plotted on the Etch A Sketch. The results aren’t exactly photorealistic, but they’re definitely better than you could achieve manually.