Fiberglass, the glass filament composite, can be used to make shower and bath enclosures when polyester is added into the fiberglass mix. Mixing fiberglass with the resin allows the material to be molded by either spraying it or pouring it into a mold. In this case, the mold is the shape of a shower or bathtub enclosure. The mold is cured into a hard laminate that is long-lasting but less expensive than acrylic, ceramic, or tile shower and bath enclosures. Fiberglass shower enclosures, like those made of acrylic, are usually made in a single piece, without a seam that might weaken at a later time.