I think I read the hint on QB, but just in case I didn't, ...
Some stores use plastic hangers with clamps on either end to hang pants, shorts, etc. The hangers come in different sizes but the clamps are pretty much standard. If you cut or saw the clamps off the hangers, you have some rather nice, strong, largish clamps.
The best part is that quite a number of the stores that use them either send them home with you or KEEP THEM AND RECYCLE THEM. Yesterday I chose the Walmart cart that had one of these hangers in it. When I checked out I asked if I could have it and got the above info. And I also got the cashier's collection of 5 more that customers didn't want! That added up to 12 free clamps. The clerk's comment was that it doesn't matter who does the recycling and if I did it, the hangers get one more use: hanger, clamps, and then recycled.
:-) Pat