Using DALPro presensitized copper clad and ARES Lite, I created the magnetic robotic arm for my line of cheapBot robots. I used a Dremel drill and its drill stand to drill out the board. The PCB still has to be populated and I hope to do that this weekend. A reed relay (and anti-kick back diode) powers the electromagnet. The PCB has drilled holes for mounting the arm to a servo. The servo allows the arm to be raised and lowered. The lifting servo and arm can be mounted to a second servo to allow the arm to rotate. But for beginners, I recommend using the robot to rotate the arm instead.
The CheapBot MagArm will allow robots to pick up slightly modified ping pong balls. This gives students the challenge of programming the robot to pick up stuff without spending more time trying to make the system work mechanically.