I stretched a king size flannel bed sheet onto my old fashioned quilt frame. It is four long sticks (1 X 3), bolted together at the corners. If there is nothing pinned to it, it collapses. But the flannel sheet pinned to it makes it sturdy and square. I found that I had to spray adhesive onto it to make it hold my pieces up. Now I have my finished large-queen sized quilt on it and I can look at every day until my next project is ready to use the wall.
The adhesive is non-permanent, so needs to be steamed to rejuvenate the adhesive properties.