Prepare the mold for application of the support shell by trimming back the flange to a straight edge around the entire mold. Gather materials used to create the two piece support shell. Begin by planning out where the support shell will split to prevent mechanical lock. Then, draw a line over the high points of the model. Using water clay, create a shim along this line. This shim will act as a separation line between the two halves of the shell. Brush Smooth-On's Sonite™ Wax over all of the surfaces that Plasti-Paste™ will come in contact with, including the base board.