The hatch cover on my boat was a (non original) translucent plastic, with a long crack covered with a patch, gasket falling off, and broken supports. While cruising up the river with the hatch open a few inches, the wind grabbed it and almost ripped it off. Shopping around, a new Lewmar is $400-500 depending on how heavy duty you get. So I decided to make my own. I bought some solid mahogany for a frame and mahogany plywood for the cover panel. It won't let in any light, but down in the v-berth that won't matter much, there's plenty of light from the windows.
Here it is, not installed yet (I need measure for new hinges and it's too cold to work outside) but I think it will be great. The 'frame' is box-joined 1-1/2" by 1-1/2" solid mahogany with a rabbet so that the panel sits down inside and is flush with the frame. Finished with red mahogany stain, clear epoxy sealer, and 3 coats of varnish. Total cost, about $100 including finishing materials. On the bottom side of the frame is a 5/8" wide rubber weatherstripping to keep water out.
Do you have any installed pictures yet?
Not yet, just got the boat uncovered and started working on the bottom. Going away to Myrtle Beach next week, so it will be a while before I get to installing it.