3x3 flood table lid

Does anybody know the best way i can build some thing similar to this? or but a flat plastic sheet of some sort some where? Considering it will be used near water and nutes, flat plywood is out the picture.
http://www.77hydrostore.com/hpg128.html

any helppppp

hellppppppppppp meeeeeeeeeeeeeeee

I was looking for the same thing, but at 3x6. Plastic plate that size is more than the lid shown, and you still have to pay shipping an cut the holes, too. You could get Plexiglas at Home Depot or Lowes cheaper and paint it, but the paint might peel off. You could use plywood and seal it with fiberglass resin maybe. Haven't tried any of these myself, so not vouching for any of them. Plexiglas would be the best if you can find a suitable paint.

Just make one out of plywood and 1x2 pieces of wood cut to the right measurements then wrap it in a vapor barrier. Get a whole saw and cut wholes to the size of your choosing.