A mobile device can include a unibody component (e.g. chassis shell) with at least a co-mold feature that isolates a contiguous portion of the unibody component from an outer portion of the unibody component. For example, the outer portion and the contiguous portion can be made of an electrically conductive material. The co-mold feature can be made of non-conductive material that electrically isolates the contiguous portion from the outer portion. The co-mold feature can be made by co-molding a resin material in a channel cut into a piece of metal and later exposing the cured resin material on two sides.