Plotclock, A Robotic Clock That Writes the Time with a Marker
Plotclock is a robotic clock that uses an arm to write the time on a mini whiteboard with a dry erase marker. After it writes out the time, it erases the numerals with an eraser and begins anew. Plotclock was designed by Johannes, is controlled by an Arduino microcontroller, and can be made with a 3D printer or laser cutter.
photo via Johannes