IRWIN Tools QUICK-GRIP Metal Spring Clamp

I have a large plastic sheet over some garden beds. This clips can hold two thin wet pieces of plastic together, no slipping, in high winds. I was very impressed. In some areas, I've also clamped that plastic to some cedar boards. They are just a hair over 1 inch thick, but the clamps fit. My arthritic hands are wimpy compared to what they used to be, so they take some effort for me to open. Before my arthritis, nerve damage, etc... I probably would have considered it easy. However, someone older and/or weaker than I might have difficulty. Any clamp strong enough to hold tight on thin plastic will be like that, though.