So ultimately I made it. Please watch it in action: https://www.youtube.com/watch?v=9NLjWsWq1YE
The two large wooden circles at top and bottom are 18" pine wood circles.
Plywood on top of lower circle is 12" square.
I used front wheel hub assembly for Chevrolet Cavalier 2000 model.
Gear is 32 teeth 3D printed one after extracting the jpg file using Simplify 3D.
Two 6.75" circles are used to sandwich the gear in between, and mounted on top of the hub.
I have included series of pics to better understand the assembly.
STL for the gears are located here: https://www.thingiverse.com/thing:3329810