I built a big turntable to gather nude photos as anatomy reference for my crazy sculpting project. As 4' x 4' seems a little bit too small for a full spectrum of poses I decided to make it 6' x 6'.
Step 1: Slabs
Cut two 4' x 8', 3/4" thick oak plywood boards (about $45 each) to two 3' x 6' boards.
Step 2: Beams
Then cut three 12 ft. long, 2 in. x 6 in. wood bars (about $7 each) into halves to have six 6 ft. bars to connect those two boards.
Step 3: Connectors
To make sure the table sturdy I used sixty 7" L-angle connectors (about $3 each) and drilled about four hundreds screws. That might have been overkill though.
Step 4: Casters
The funnest part was attaching casters. I used sixteen Titan polyurethane rigid casters (about $10 each).
Step 5: Ready for Photo Shoot With Models!
As long as casters are oriented along the circumferences of concentric circles, the turntable will rotate around that center.