3D printing combined with Arduino has been really allowing many diy'ers to create practically anything they can imagine. Combining the Arduino board with a 3D printer is a powerful tool for sure. Check out this clock that is on Thingiverse. All the plastic pieces are 3D printed, and an Arduino board is programmed to have this writing clock function correctly. Clearly the clock is not practical, however it certainly would be a conversation piece for a few hours until the eraser gets too saturated in ink, or the ink runs low in the pen .Here are a few images followed by a video of the clock in action: