Shell Shock® brushable plastic and Plasti-Paste® trowelable plastic can be used in combination to create a rigid, strong, inexpensive mold. A mold created from these materials can be used for casting silicones directly without a mold release.

Constructing a core in the mold allows for a thin walled casting that uses a minimum of material. The hollow casting is then filled with inexpensive urethane foam to provide support.