Abstract: A method of forming a structural article from a shape defining interior member (20) and at least one external skin (22). The interior member has at least one surface (23) with channels extending to the periphery thereof. The method comprises heating a thermoplastics sheet intended to form said external skin (22) and bringing the heated sheet (22) alongside the surface (23) of the interior member (20) and into initial contact with same. A fluid pressure differential is then applied between opposite surfaces of the interior member (20) and the sheet (22) to conform the sheet (22) to the shape of the interior member (20) and mutually engage same. Fluid trapped between the sheet (22) and the member (20) escapes through the ends of the channels of the member (20) as the sheet (22) is drawn into substantially conformity with the surface (23) having the channels. The fluid pressure differential is maintained until the sheet (22) has cooled whereupon tensional forces arise in the sheet (22) in all directions.

Abstract: Structurally strong articles are formed from inherently weak materials, such as expanded polystyrene, coated with one or more layers of a thermoplastic sheet material, such as amorphous polyethylene terephthalate. The inherently weak interior members are either fluid permeable or perforated. These members are sandwiched or encapsulated by heat deformable outer layers. The articles are made by applying a fluid pressure between the stack of interior members and the thermoplastic sheet, with the thermoplastic sheet heated to conform to the interior members. The fluid pressure is maintained until the thermoplastic sheet is cooled so that tension extending in all directions is produced in the sheet. The resulting articles are useful as building elements, signs, motor vehicle panels, pallets, surf boards, and sail boards.

Abstract: The present invention discloses structural articles such as helmets, cooler chests, pallets, building boards and a large number of diverse articles all formed from an inner, preferably air permeable, body to which a structural strength imparting skin or layer has been applied to either a single surface or opposite surfaces. The body can be expanded polystyrene, wood, particle board, cellulosic fiber cement, GECET or CARIL. The sheet or skin can be acrylonitrile butadiene styrene (ABS), polyester, styrene, or polycarbonate. Amorphous polyester (APET) is particularly preferred. A method of forming such structural articles and apparatus for use in carrying out the method are also disclosed.