You don't have dimensions for your design do you? It's very nice. Looking to build something similar.
I would kill to get a digital copy of exact dimensions. I think this would be somewhere but I haven't seen it. Would be so easy to laser cut a variety of covers. My plan involves using aluminium to support the top, but I really like the shape of your design, will probably modify mine to match.I had a template. key word had. my puppy got in the garage and ripped it to pieces...this is my first attempt and I am happy with it but I still want it to be able to stop water from getting in trunk. the issue I am having is around the rollbars. since I want it to be used like a regular trunk and open. finding the right weatherstripping is hard. as it keeps falling off or peeling off. or it makes it difficult to shut all the way.
couple things I would do
-get it waterproof around the roll bars
-use metal for the piece that holds the "trunk" in place when closed. as after putting on the bedliner. it sticks a little on hot days
I can go measure it and post it later. after the initial template it was a bunch of trial and error. especially for the 2 front side pieces.
it you get a 4x8 plywood. you will have enough wood to make a few mistakes and adjustments on every piece except for the part that opens.
one of these days I will do a write up