I first found these 12 inch bungee cords at Herman's
Sporting Goods. They came in multiple colors and I found them perfect to
hold my frames securely to the grid walls I was using. Always hang on two
hooks so you don't spend the entire show straightening the work. By
purchasing enough of them, I was able to match the color to the
photograph...
I just found a
supplier who sells them in a Google search. They come in packages
of multi colors as seen below.
If you can't find them, you can always use a rubber band
with two paper clips as shown below.