ya know, that looks like it would be fun enough to keep me interested. I love my Fluidity, but that looks like it could move in on my "dancey" dvd territory.
I know I think it will be different then all the other Firm videos but still kick my butt hopefully. I will deffinitly be getting it as soon as it comes out, depending on the price though. Some of there stuff is sooo expenseive then drops a few months later.
One of those round plastic sleds? But, overall, the shape wouldn't be right. I can't think of anything else you could find.
My first thought was that a woodworker could repeatedly cut the curve out of wood, then glue the pieces together to get the width. The interior curves could even be routed out to decrease the weight. I wouldn't think you'd want to do that to the two end pieces, though.
You could also build the skeleton out of wood and cover it with fiberglass, but not many folks have the skills and materials for that!
You could also cut out the curves for the edge and then nail a structure between those two pieces. You'd have to make sure the exterior curves are what stayed in contact with the floor to ensure the smoothness. So, from the side, you'd see the crescent with a bunch of nail heads around the edge, as opposed to seeing the edges of the cross pieces. I don't think this would be as strong as my first wood plan.