The measured mechanical properties of conventional lightweight metallic foams fall far short of those predicted by idealized models for closed cell foams. Their poor mechanical performance can be attributed, to a large extent, to curved and corrugated cell faces present within the foams. Idealized honeycombs and foams with idealized cell structure and curved or corrugated cell edges and faces are modeled using finite elements. The elastic modulus and plastic collapse stress of these honeycombs and foams are calculated relative to those of a comparable cellular material model with flat cell edges and faces. The results are presented in terms of the radius of curvature and the amplitude and frequency of the corrugation.