Large Carboard Box
The first thing needed is a hula hoop. If you do not have one then anything hard and flexible enough to make a circle will work. get some foil, a belt and a cardboard box. now your ready to begin
Sit the hula hoop or other circular object on the floor. Take your cardboard box and cut a circle big enough to fit inside the circle. Tape the cardboard box the the circle. Next take the foil and cover the whole thing (including the circular object) up with it. Now take the and put around the circular object only (not on the cardboard. make a hole in the middle for the person to fit in and cut two holes on each side of his body. Put the belt through the little holes on each side and tighten the belt up to comfort and that's it.