When we think of fiberglass, we think of the smelly, toxic resins used to reinforce it. Many props people avoid fiberglass for that reason. Water-based resins offer a less toxic alternative. Aqua Resin is one brand which is useful for theatrical prop building with fiberglass. You need a dust mask when handling the powder, but once mixed, it is non-toxic.
In my latest video, I show how to make a prop using fiberglass with Aqua Resin in a one-piece negative mold.
Using fiberglass is one of the techniques that now has a step-by-step photo tutorial in the second edition of The Prop Building Guidebook: For Film, Theater, and TV, which comes out February 10, 2017. You can see all the companion videos at the Prop Building Guidebook website.