Freestanding Greenhouses – Custom built polycarbonate greenhouses are often a wise choice for the builder. The Sundance Supply approach is a Multiwall Lexan Polycarbonate sheet covering and the Base & Cap Installation System. The customer provides the frame, and the remaining building components, for an elegant structure. Together this approach provides a watertight, attractive and long life solution, often costing less than a prefab greenhouse. Substantial savings, over kit pricing, can be achieved.