While plate lattices exhibit superior mechanical performance compared to truss lattices at equivalent densities, their fabrication on an engineering scale presents significant challenges, particularly when utilizing structural materials for load-bearing applications. Industry and academia predominantly rely on 3D printing techniques, but encounter limitations in feature size and scalability of energy efficiency for high production rates. In this study, we propose a modular origami design and manufacturing method for creating steel plate lattices at the meso-scale using sheet stock. Rigid-foldable unit cells are cut, folded, and discretely assembled into lattices. Their mechanical performance is simulated and mechanically tested.