46 may be made of various polymer or predominantly polymer materials e g a polyisocyanurate polyurethane polystyrene or phenolic material or a material made of a blend of these materials a polyisocyanurate polyurethane polystyrene or phenolic foam material or a foam material made of a blend of these materials a predominantly polyisocyanurate polyurethane polystyrene or phenolic material with up to 40 by weight but typically between about 1 and about 25 by weight organic and or inorganic filler s or a material made of a blend of these materials with up to 40 by weight but typically between about 1 and about 25 by weight organic and or inorganic filler s a predominantly polyisocyanurate polyurethane polystyrene or phenolic foam material with up to 40 by weight but typically between about 1 and about 25 by weight organic and or inorganic filler s or a foam material made of a blend of these materials with up to 40 by weight but typically between about 1 and about 25 by weight organic and or inorganic filler s a material made of other thermoset matrix polymers etc however a preferred material for the insulation core layers 60 and 70 and the reinforcement layers 62 72 and 78 is a polyisocyanurate material or foam material or a predominantly polyisocyanurate material or foam material with up to 40 by weight but typically between about 1 and about 25 by weight organic and or inorganic filler s examples of various fillers that may be used in the predominantly polymer materials of the insulation core layers 60 and 70 and the reinforcement layers 62 72 and 78 include but are not limited to powdered liquid and fiber fillers the polymer or predominantly polymer materials of the insulation core layers 60 and 70 and the reinforcement layers.