I can't claim credit for figuring out how to make the hoop itself. For that, see the JasonUnbound website http://www.jasonunbound.com/hoops.html
. There, you'll find excellent instructions on making a great hoop! As for materials, I got my tubing and connector from US Plastics
. I ended up getting a 100 foot roll of the 1" PE Flexible Pipe Not-NSF Listed 80 psi. Ended up making about 8 hoops with this, so on a per hoop basis, it's pretty cheap!
When making your hoop, there is one modification that needs to be done to the JasonUnbound version: File/cut off the ridges on one side of the tube connector. Cutting off most of the ridges as shown in the pic will allow you to take the tube apart when you need to replace the batteries, but still keep the tube together while hooping.