To improve the stiffness of a thin single layer or mono-sheet of steel, a composite steel comprising at least two outer steel layers separated with a spacer. Spacer materials can include any metal less dense than steel, or a polymer or resin, optionally comprising a carbon or glass fiber, or Kevlar material. Such a composite steel can yield a higher stiffness than a mono-sheet of steel having the same total sheet thickness. For instance, moving the steel material away from the neutral axis with the spacer can increase the strain on bending to provide a high strength composite steel that maintains stiffness while also providing desirable weight savings.