Cut a 3/4-inch piece of plywood into a circle that matches the table top.
Sand the entire circle, then paint or stain it to match the existing table if desired. You can also leave it the natural wood color if you prefer.
Place a heavy-duty lazy susan bearing on the center of the table top. This bearing consists of two metal rings that are joined with ball bearings, allowing them to swivel.
Screw the bottom ring of the bearing to your table using the included screws. No pilot holes are needed.
Rotate the top ring a quarter turn and mark the location of the screw hole on the table with a pencil.
Drill a 1/2-inch hole through the table top at the pencil mark.
Place the plywood circle on the floor.
Turn the table upside-down and place it onto the plywood circle, lining up the edges.
Rotate the table until one of the bearing's screw holes appears in the 1/2-inch hole that you drilled.
Screw the bearing to the plywood circle through the 1/2-inch hole.
Continue rotating the table and screw the rest of the bearing to the plywood circle.
Turn the table rightside up again. It now has a table top that can spin.