How to Make Fiberglass Stones

Spray two thin coats of silicone mold release into the silicone mold, allowing the first coat to dry before applying the second.

Tear the fiberglass mat into 5-inch squares. Cut the fiberglass cloth into squares of the same size with a pair of scissors.

Put on a pair of rubber gloves.

Mix a batch of polyester resin with its catalyst in a disposable bucket. The exact mixing ratio will be printed on the resin container.

Brush a coat of catalyzed resin on the entire inner surface of the silicone mold.

Press squares of fiberglass mat into the resin, overlapping them by a quarter inch. Cover the entire inner surface of the mold with fiberglass.

Tap more catalyzed resin into the fiberglass with a paint brush. This will saturate the fiberglass and force out any trapped air bubbles.

Add two more layers of fiberglass mat and resin, followed by two layers of fiberglass cloth and resin.

Allow the fiberglass to dry completely until it has hardened.

Peel the silicone mold off the fiberglass stone.

Cut the jagged bottom edge off the fiberglass with a saw. Put on a pair of goggles and a dust mask for this step.

Paint the exterior of the stone with fiberglass primer.

Paint the stone whatever colors you want. You can use acrylic craft paint, an airbrush or even spray paint (there are many stone effect paints available).