An insulating part for an electronic device includes a first metallized outer surface capable of cooling one or more electronic components disposed on the insulating part. The insulating part also includes one or more additional metallized outer surfaces, such as a set of cooling ribs, to provide improved cooling for the electronic components. These additional outer surfaces are coupled electrically and thermally to the first metallized outer surface, and to each other by recesses containing a heat transfer element, such as a metallization or a soldered connection. Thus, heat transferred to the first outer surface is further dissipated among the several additional cooling surfaces.