Airsoft Red Dot Protector

I needed a quickly printable, easy-to-change, cheap protector for my Red Dot sight. So I designed this. You can print it in place, no need for support or raft. You need a clear polycarbonate plastic sheet. 2 mm thick would do it. You need to cut a 50x39 mm rectangle from it. Just glue it in.
You'll also need a 40 mm long M3 screw with a nut. I chose the one with the internal hex head, because you probably carry one with yourself.