Make the Mold
It will be necessary to make a mold to form the bricks. Whitman used a mold which measured 20" x 10" x 5". A mold can be constructed using pre-cut lumber. Use Dr. Whitman's dimensions or make a smaller version. Other items can be used as a mold rather than having to construct a mold from scratch, for example: small milk cartons, plastic blocks, cardboard shoe boxes, or Tupperware containers.