Sorry mate, I can't find any better images than those I posted here:-
Early Dive boats and Flatacraft Force 4's
The screen is just a flat sheet, so again a thick paper or card template could be mocked up first to get the shape how you want it.
The early ones did have a small Lip turned over across the top edge, but Flatacraft soon gave up with them and supplied any replacements without it.
If you look carefully you can see it in the very early image of Anna XXV on the slipway.
The material you use will need to be quite strong, as we always found passengers first reaction when getting in or out was to grab the screen for support and could break it.