Jose Julio has taken a 3D printer and turned it into an air hockey opponent.  Using parts of the 3D printer, an Audrino board and a PS3 EYE camera, the system can track the puck and respond accordingly.  With its need to move accurately in the x/y direction, it’s easy to see why your 3D printer could be an excellent opponent.  You can read more about it from Jose’s blog or go to GitHub to get all the information to build your own!