A preform for impregnation of a metal or ceramic matrix material comprising a multiplicity of reinforcement particles bonded together so as to define a three-dimensional, open-cell reticulum comprising a plurality of randomly oriented thread-like portions interconnected one to the next via a plurality of nodes. A reinforced composite made from such preform and method of making the preform is disclosed/claimed wherein the reinforcement particles are mixed with prepolymers used to produce a fugitive binder for the particles comprising a foamed polymer, and the particles align themselves with the polymer portions of the resulting foam.