Set up your work area in a well-ventilated room with protected surfaces. Put on a vapor respirator, latex gloves and safety goggles before you begin your fiberglass sculpting.
Coat the inside of your mold or the outside of your base form with a release agent. Let the mold release agent dry completely.
Mix together a small amount of resin in a bucket, following the percentage guide for your particular resin product. If you are working with a mold, paint a base coat of resin into the bottom of the mold and let it dry.
Cut your fiberglass cloth into small strips. Soak a fiberglass strip with the resin and lay it into your mold or over your skeleton form. Smooth the cloth down, sculpting the fiberglass into the desired shape. Paint over the cloth with more resin.
Soak more pieces of fiberglass cloth in the resin and layer them into your mold or form, until you use up all your resin.
Mix together another batch of resin and continue layering wet fiberglass over your form. Lay down two or three layers of fiberglass cloth, covering the entire surface.
Let your fiberglass sculpt dry for two hours. In the meantime, clean up your work station. Throw out any materials the resin touched, and clean up any spills with turpentine and a drop cloth.
Break the "seal" on your fiberglass sculpt by removing it from the mold or form. Place the fiberglass pieces back into the mold or back onto the form to continue curing, for several more hours.
Put on a particle respirator and your safety goggles. Sand down all jagged and rough spots on the fiberglass sculpt until you have a smooth surface.