[sanddrag]

We took some 3/8" 7075 aluminum rod and drilled and tapped one end. Then we put a chamfer on the other end and drilled a transverse through hole. These became our "bumper pins" these were screwed to a 1/8" metal plate, abut 1/2" wide and 2" long with three holes, one for the pin, and two to screw it to the wood in the bumper. We 4 of these sticking out of the bumpers on either side of the robot. They would go through 7/16" holes in the frame, and then hitch pin clips were placed through the transverse holes to secure it. Then we used a tee nut in each end bumper piece (the small front and back bumpers) with a 3/8-16 knob bolt to secure it. The end bumper pieces were attatched internally to the sides, with aluminum angle.