Here is a device I call the Hack-a-Sketch. The screen is a normal laptop (an old one), but it has real knobs which control the stylus on the screen.
An Arduino board reads the inputs from two potentiometers (the knobs), and sends the information via USB to a Processing sketch which displays the path of the stylus on the screen. This was extremely easy to build because the Arduino is just running the StandardFirmata firmware. No custom code on the board. The Processing sketch was surprisingly easy to write. Using this really did feel like using an Etch-a-Sketch.
How did I erase the drawing by shaking the computer? There’s a mercury switch hidden behind the panel holding the knobs. When the code senses shaking, the image is slowly erased. More shaking = more erasure.
Ovvero come trasformare grazie ad una scheda Arduino un vecchio notebook in una lavagnetta magica Etch-a-Sketch style.