[tsubaki]

There is a grade of plywood used for form buliding, how available it is I don't know. It used to be distinguished by the outer edge being painted a burnt orange color. We have used this plywood for replacing casting decks on boats and on the ramp to the dock. One side is usually waxed heavily so as to be able to release from the poured concrete. The last time I bought it was a couple of years ago at Lowes and Homedepot. The glue in this plywood is about as good as marine grade. If you find it and use it be sure to wipe or sand off the wax before applying the resin.