A unitary structural assembly including a first component having a plateau-receiving aperture and a compression-molded, composite second component having a sandwich structure is provided. The second component includes a first outer layer, a second outer layer, and a core positioned between the outer layers and having a large number of cavities. The outer layers are bonded to the core by a press molding. A portion of the second component including the first layer and the core defines a raised plateau having upper and side surfaces. The plateau has a size and shape corresponding to the size and shape of the plateau-receiving aperture. A height of the plateau corresponds to the depth of the plateau-receiving aperture. The plateau is inserted into the plateau-receiving aperture so that corresponding surfaces of the plateau and the plateau-receiving aperture are in abutting engagement to unitarily connect the components and form the assembly.