On our robot, we used 0.07 inch thick acrylic as a guide to help align the hang. Whenever I would throw something over the fence, it would bend the acrylic to the point where it would shatter. Is there a way to solve this? Is there a better plastic that is legal? Are we allowed to use a lighter to heat it up so that it’ll become more malleable (as long as we don’t melt it)?

Use polycarbonate, it won’t shatter. Acrylic is something different, shatters, and is illegal.