I would like advice on what type of epoxy, fabric and how many layers I need to build a water tank about 56” long x 20” wide x 10” high. I removed the rear seats from my F350 Supercab and want to build about a 40 gallon water tank that will conform to the floor. I will pump the water into my slide-in camper when the water there runs low. Being in the Styrofoam business we can make a perfect male mold in expanded polystyrene foam, fiberglass around it and then cut the tank in half to remove the mold. I assume we can bond the two halves back together. How many layers of what type of fabric do we need? For the large horizontal surfaces I plan to bond ¼” birch plywood to stiffen the flat surfaces but everywhere else we need adequate strength in the glass matrix.