a structural panel comprises a metal and paper composite in which the metal outer skins have a minimum thickness of 0 . 005 in . exceeding foils and a maximum thickness of 0 . 012 in . while the paper core ranges between 0 . 01 in . and 0 . 05 in . the panel is a stiff , lightweight substitute for thicker metals and may replace light metal sheets such as aluminum with a composite in which the metal skins comprise sheets from heavier metals such as steel . the paper core is a web which is adhesively bonded to the metal skins and which may have openings to create paths for adhesive bridges between the metal skins to minimize failure caused by buckling .