Abstract: A composite beam built up in box form of four metal members, two flanges and two webs, that in some applications are of different thicknesses. The flanges and webs are cold roll formed light gauge aluminum or steel, or in extruded form, and the hollow box shape is filled with a structural honeycomb or foamed plastic, or an alternate lightweight bulk space-filling substance. The four metal members are two pairs of duplicate members formed and bonded around a core with staking or peening operations accomplished during beam box forming assembly.