a method for making foam structures suitable for use as mechanical energy absorbers , structural members , filters , catalyst carriers or the like . a composite rod comprising an outer shell and an inner core is formed of respective mixtures of powders . the mixture for the outer shell comprises a sinterable powdered structural material such as ceramics , metals , intermetallics , and a powdered binder such as paraffin , wax or polymer . the inner core comprises a powdered channel - forming filler material such as melamine or polymers , or soluble inorganic compounds or a metal that can differentially be removed from the structural material of the shell . the composite rod may be formed by extrusion . the composite rod is sectioned into a plurality of composite rod segments of predetermined length and a plurality of these segments is assembled in randomly oriented relationship to one another . the assemblage of rod segments is then consolidated , and the binder and filler are then removed , as by heating . the remaining structure of the outer shells , comprised of ceramic or metal , as the case may be , is then sintered to produce the foam structure . in certain embodiments , the material of the inner core may be removed by heating it in the course of heating the structure to perform the sintering step . in other embodiments , the binder and / or filler material may be removed by means of a suitable solvent .