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