The Time Plotting Clock mechanism is fantastically simple, 3 tiny servo motors allow the erasable marker to be moved along the drawing surface and raised when no contact with the surface is desired. This allows the pen to write the time. There is also a tiny eraser located in the upper right corner, when the next minute is ready to be drawn the pen grabs the marker and erases the previous time before drawing the new time.
Via Hacked Gadgets.
Check out the video after the break.