Abstract: A polymeric composite structure having a polymeric shell layer with a finish-side and a non-finish side and a cross-linked thermosetting polymeric backing layer and method of manufacturing thereof is provided. The cross-linked thermosetting polymeric backing layer is simultaneously molded to conform to the shape of and bonded directly to essentially the entire non-finish side of the polymeric shell layer. The method includes forming the polymeric shell having a finish-side and non-finish side into a suitable shape, placing the shell into a mold, and introducing an uncured blended mixture of unsaturated thermosetting polymeric backing material and cross-linking promoter into the mold to force the backing material to directly coat the non-finish side of the shell.