ColSebastianMoran
( IRL Richard Karash )
seven thin metal or fiberglass wands. four of them the same length for the uprights and three longer ones for the crossbars. I made mine hinged so they would collapse when not in use. You cut them to the correct length to fit the bag size. The only tricky part is finding the hinge that you want to use. I took a wooden spool that looked like a yoyo and drilled holes where I needed them and pushed the wands into the holes. It was very secure.
Tinker-Toy rig? Or use one of the more current kids construction sets?
To hold the bag up away from hands.