The clamps idea is good. You can also screw a piece of plywood to it front and back or just one side. You can wrap it in tar paper the using small screws tighten the paper to the frame.kymike said:Just looked at the pic again. Didn't even notice the car. Lol. I think those people would be upset to come out and find their car full of holes. I did fill the bottom with sand. I was thinking about doing a piece of cardboard zip tied to the side posts then put my target on the cardboard. I'm open to ideas on this though.