A method of forming an internal structure in a hollow component that includes the steps of forming an assembly having first, second, and third plates the first and second plates each with a substantially planar surface and a surface that includes at least one protrusion and is on the exterior facing surfaces of the assembly. The third plate is sandwiched between the first and second plates. The method also includes the steps of selectively bonding portions of the third plate to sections of the first and second plates substantially opposite the at least one protrusions of the first and second plates; and forming the assembly against a die such that the at least one protrusions of the first and second plates are transferred from the exterior facing surfaces to the interior facing surfaces of the first and second plates.