Fiberglass is made of natural minerals and some manufactured chemicals. The basic raw materials are silica sand, limestone and soda ash. Fiberglass is often made of recycled glass as well. The raw materials are mixed together, after being carefully weighted in the exact quantities, in a process that is called batching, and then melt into glass. Following thereafter, the molten glass is transferred to the forming equipment, passes through superfine holes, where very thin filaments are created. Fiberglass is the material of choice for making relatively inexpensive shaped shell structures, like large covers with round corners or complex shapes, as it offers flexibility in design. Manufacturing with fiberglass is cost-effective and affordable not only because it saves maintenance costs due to its durability, but also because the final product is lightweight, which results in less storage and shipping costs.