Abstract: A modular lightweight structural panel is made of a lightweight expanded plastic filler reinforced by wire lattice structures. A number of long, narrow filler elements are interleaved with a number of substantially flat lattice structures to form a laminated panel subassembly with corresponding surfaces of the filler elements collectively forming substantially planar surfaces of the panel core. The subassembly is laterally compressed, in a direction perpendicular to the planes of laminations, to thereby force each of the lattice structures to be pressed into and partially embedded in mutually contiguous surfaces of adjacent ones of the filler elements.