I am not sure to the stlye companion hatch you are talking about. If it is the drop boards, ask Hunter if they can make them out of lexan but the cost is high. Otherwise you would need to look for scrap material to make them out of as most only want to sell you a 4 by 8 sheet.
You could also go to a windshiled shop and they might help you with the lexan. Otherwise, teak, marine grade ply and so forth. Make sure the cuts are beveled upward to prevent water coming into the cabin.
If you are talking about the slider hatch, then I would agaion go to a marine yard to see if they have pieces of glass. If you cut it yourself, cut at a low speed. Again the material or lexan is expensive. If glass or even lexan, go back to Hunter as they have the basic diemsions but to make sure, measure it yourself before going to hunter.
