ok. coping can be easy or hard. you can recess the metal L coping into the plexy, but that involves cutting the width and height of the coping out of the edge, so the whole thing is almost flat, with the metal a bit higher. In order to make sure that the initial force of slamming your skis into your box is absorbed through the metal. in this example, the screws go through the metal, which is countersunk, AND through the plexy, anchoring the whole thing together. PIC: plexy is red, and coping is black.
screws would also go horizontally through the side of the coping, to keep it more stable.
The other option is to cut your plexy a bit short on both sides, and using a pipe of that diameter, use that for coping. the sides would have to be lower, so the pipe is almost level, and you could fasten it however you wanted. my personal favorite is welding a flat piece onto half of the pipe, so it makes a semi circle, drilling holes, threading them, and then usuing screws of the same thread to anchor it from the bottom, so there are no holes. that requires welding skills, however, and a grinder to cut the pipe in half, plus a threading tool.
