Fiberglass, or more accurately, Fiberglass Reinforced Plastic is a popular tool in making both rigid molds and structurally resilient props.


Fiberglass moldmaking can be used to produce temperature resistant, lightweight, long lasting durable molds. Unlike plaster molds, properly made fiberglass molds allow some degree of flexing without damaging the mold. This generally makes unmolding simpler and reduces the risk of damaging both the cast piece and the mold in the process.

The time, tools, and materials involved make fiberglass molds significantly more expensive than plaster molds. The noxious chemicals involved can present both safety and environmental concerns. Proper safety equipment is non-negotiable. Cleanup is also more difficult, so a proper drop-cloth and work clothes are imparative. trimming and adjusting a fiberglass mold is more difficult as well. Any simple steel tool may be used to adjust minor defects in a stone mold, whereas a rotory tool and special blades are reccomended to modify cured fiberglass.

In larger production houses, the use of a fiberglass choping gun can make very quick work of producing large fiberglass molds. However, this is cost prohibitive for use in the smaller scale.


Fiberglass layupEdit

This is the process of applying layers of fiberglass into the cavity of a mold to make a prop. The result, when done properly is a high detail piece that requires little to no finishing.

Fiberglass over foamEdit

This is a common technique used to make larger props. The technique is effectively borrowed from the techniques used in sufboard manufacture.

Vacuum bag curingEdit

This process may be used as a final step of any fiberglass project. It involves placing the uncured fiberglass into a bag which is then voided of air. The bag conforms over the surface and compresses the layers of fiberglass. The vacuum voids both airbubbles and excess resin, resulting in a flawless, and more durable piece.