A process of making a multi-layered product from an extruded sheet or web of material (42) having parallel upper and lower walls (130) and a plurality of spacers (134) extending between the upper and lower walls (130) is provided. Portions of the extruded web or extrudate (42) are removed in selected areas. The lightened web is then folded. Outer skins are then applied to the folded web. The extrudate (42) is formed into a product (10) having a plurality of cells (14). The cells (14) may have one or more openings (34), allowing access to an interior of the cell (14) and reducing the weight of the product (10).

The invention relates to a method for producing a fiber-reinforced, polymeric continuous profiled element (1), wherein the continuous profiled element (1), having preferably at least one hollow chamber (2, 2), comprises a core profile (10) which can be produced by means of a pultrusion process, and wherein during the pultrusion process at least one continuous strand having reinforcement fibers (5) is integrated into the polymer matrix (4) of the core profile (10). According to the invention, the curing of the core profile (10) is carried out by means of a dual-cure method.