We set out to build an airhockey table with mechanically controlled paddles. We wanted each paddle to be able to move in both the x and y dimensions under fully autonomous computer control or by a person with a Nintendo 64 controller.
After we started building the table, we had to scale down our idea to something that we could build in the alloted time. We ended up with only one mechanical paddle that could only move in the x dimension. This simplified the mechanical building aspect tremendously. The single paddle could still be controlled by the computer or by an N64 controller.