[GeeTwo]

We did a turret on our rookie robot with about 200 degrees of rotation. We used a lazy susan bearing and chain attached to the turret with screws. Turning was done with a window motor and about a 22 tooth sprocket, I believe. Not pretty, but it worked.

As we thought later about other ways to do this (including continuous rotation solutions), in addition to solutions similar to those I've seen here, using the teeth of an auto flywheel also came up.

The biggest problem with a continuous rotation turret is that if you want to put anything active on it, you need slip rings or similar. These aren't too expensive for signal level, but those with enough size to power some motors and more than two wires don't come cheap. Larger slip rings often have mercury.