[PAR_WIG1350]

I, personally, would take 1/16" - 1/8" polycarbonate sheet and make a 2 loops, one for either size to act as springs to catch the arm and slow it. For 1/8 inch material, a larger loop would probably be used than for a 1/6 inch loop, but testing would have to be done to determine the right size based on a number of factors.