i was skeptical until we made them the other night, but these board really do help with balance. it's helped me with my switch balance just in the last 3 days. and it's way better than paying 100 bucks for them.
here's what we used:
1/2 inch sub floor, which is basically plywood (we just found some lying around, but you can get it at lowe's or home depot)
4" pvc pipe. we got a 5 foot piece for under 10 bucks. you can make 3 rollers with a 5 foot piece of pvc pipe.
we made our boards 16" by 32" (I made mine a little longer, since i'm taller than jason is). the original indo board is an oval, so you can cut an oval if you want, but we just cut rectangles and rounded the corners, since it's easier. after we rounded the corners, we took a sander and smoothed the edges so they weren't rugged, and to prevent splintering.
we are still experimenting, trying to find something inexpensive to keep the board from sliding on the pvc pipe. for the time being, we used duct tape. we spent 12 dollars, and about 2 hours making the boards. there wasn't much preplanning or anything, we just did it.
we are thinking about grip tape for the top, like a skateboard, and doing some graphics and stuff. and maybe making a lip on the bottom ends of the board, like the real indo boards, to catch the board from rolling all the way off the roller.
here are a few pics. the piece of wood is only there cause the front lawn was the only place we had to test them out. they don't roll very well on grass.