Referring to FIG. 12A, the second metal part 220 may include a bridge 1122 making contact with the first metal part 210. A plurality of bridges 1122 may be formed. The bridges 1122 may be removed in the operation (e.g., the operation 1060 of FIG. 10) of machining the side member and may tentatively fix the second metal part 220 to the first metal part 210 before the operation (e.g., the operation 1050 of FIG. 10) of forming the polymer part.
In an embodiment, the operation (e.g., the operation 1050 of FIG. 10) of forming the polymer part (e.g., the polymer part 230 of FIGS. 7A and 7B) may be performed by injecting the polymer material into the first metal part 210 and the second metal part 220. For example, the operation of forming the polymer part 230 may include an operation of filling the cavity 1211 of a mold 1210, in which the first metal part 210 and the second metal part 220 are located, with the polymer material.
