Fiberglass is exactly what its name implies: fibers made from very fine glass. It is popular for its ability to be manipulated into almost any organic shape and then hardened with a resin for lasting durability. Building with fiberglass is a complex, two-stage process, the first stage of which is constructing a solid form of the object you'd like to cast in fiberglass.
Instructions
1. Glue your sheets of Styrofoam together using the expanding foam, which will act as your adhesive. Spread an even amount of spray foam across the top of the sheet, staying approximately 1 inch from the edge--the spray foam will squeeze toward the edge and out the sides as you lay a second sheet on top. Repeat the process, adding more sheets until you create a block large enough to accommodate the object you are trying to create.
2. Once dry, rough-carve the foam with a keyhole saw or an electric carving knife. Refine the shape with your Surform tool until you've achieved the desired look. Finish the form with a coarse sandpaper.
3. Coat the entire form with drywall mud. Several coats are needed to thoroughly seal the Styrofoam from the fiberglass resin.
4. Wait for the drywall mud to dry, then smooth the form with the fine sandpaper.
5. Coat the entire object with several coats of fiberglass resin. Let it dry, and your fiberglass form is finished.
