How make a 6x6 board rotate using LEGO technic parts? Are there any common patterns for making a 6x6 (or bigger) LEGO board have a ability to rotate using technic with gears and such? Has to be without the help of the existing 2x2 lego part that rotates, its not big enough.

Seen from above:
You can use a large gear (3649) with connector pegs (970607) attached like this: 


Then you can attach the 6x6 plate on top.