A method for making a metallic casing includes providing an apparatus comprising a first mold and a second mold, placing a preform into a rectangular depression of first mold, moving the first mold to the second mold so that each sharp edge is substantially coplanar with a corresponding cutting edge, moving the first mold to the second mold so that the cutting edges are beyond the corresponding sharp edges of the first mold to complete a partial cut procedure, and moving the first mold to the second mold so that the secondary-cutting edge moves beyond the corresponding sharp edge and completely cuts the excess off the side wall.