Here are a couple pictures of resin bonded sand molds for cardboard patterns. Note how thin the molds are. That is because there is only a thin piece of cardboard in each mold. Although the cardboard pattern is 3/8ths of an inch thick the mold needs to be 4 inches thick to keep the 2,000 degree metal from burning out of the mold. The 3 benches will require 3,300 pounds of sand and 600 pounds of bronze.