Abstract: A composite insulator is formed having evacuated hollow plastic enclosures arranged in a closely packed configuration with a foamed plastic resin filling the interstice between the plastic enclosures. According to a preferred aspect of the invention, hollow evacuated spheres are embedded into a matrix of polyurethane foam. The composite insulator can be formed directly within an insulating cavity of an appliance or can be formed into customized panels which can be inserted into an appliance. Also, disclosed is a method of manufacturing the composite insulator by forming a seamless continuous plastic wall on a molding chamber that has been at least partially evacuated, incorporating the resulting hollow plastic enclosure into a plastic resin which is capable of being foamed in place, introducing the composite into an enclosed cavity that is to be filled with insulation, and causing the plastic resin to foam in place.