This is a display stand with an inbuilt planetary gearbox, that allows you to reduce the turning speed. There are two types, a 2:1 gear ratio, and a 4:3 gear ratio.
This design allows you to display an item on it, and rotate it with minimal effort. To use it, twist the outer ring (Silver in my picture) and the upper gold plate( Known as the Display Plate) will spin in the same direction, but slower.
Standard Skateboard Bearings 3x (you can 3d Print these, at THIS LINK)
15% infill, 0.4 layer height.
Print the base at higher infill so it holds to the ground better.