Polyester resins are used in large volume as a binder for glass fibers to form structural panels and rigid heads for costumes. Like the epoxies, they are usually made to harden by chemical action rather than by the evaporation of solvents and thus cure with little shrinkage.

Parts of complex shape can be built up over simple forms or in more elaborate molds by applying successive layers of glass fiber cloth or matting and polyester adhesive or binder. The curing of the resin is accelerated by heat.