I built the first doodle clock http://hackaday.com/2012/03/14/robotic-doodle-clock/ 3 years ago as a joke. But to watch the clock work was so mesmerizing that i wanted it to be a practical desk clock. The biggest problem with the first clock was the drying up of the markers after just 30 minutes of working. So the solution to that i found was the magnetic writing boards http://www.walmart.com/ip/Fisher-Price-Doodle-Pro-Basic-Purple/26012794 made for children. I used 2mm cylindrical magnets inside a solenoid to write and erase the text. Next i replaced the servos with small geared steppers to make the clock very silent and smoother. And finally all parts were designed and 3d printed . I also got the final pcb manufactured .