You can follow the build in this video.
You will need:
1 x 21"x14"x1/2" birch plywood
2 x 3/4" copper pipes (length of your choice)
4 x 3/4" copper pipe plugs
14 x 2", 1/4" bolts
4 x 2", 3/8" bolts
28 x 1/4" nylon threaded nuts
8 x 3/8" nylon threaded nuts
28 x 1/4" spacers
24 x 3/8" pressure spacers
4 groove ball bearings (search in Amazon)
Optionally: 3 x 2.5", 3/8" wooden bolts (if you plan to attach to ceiling or any surface) Paint (optional)