An integrated multilayer assembly (100, 200, 300) for an electronic device comprising a first substrate film configured to accommodate electrical features on at least first side thereof, said first substrate film having the first side and a substantially opposing second side, a second substrate film configured to accommodate electrical features on at least first side thereof, said second substrate film having the first side and a substantially opposing second side, the first sides of the first and second substrate films being configured to face each other, at least one electrical feature on the first side of the first substrate film, at least one other electrical feature on the first side of the second substrate film, wherein the at least one electrical feature or the at least one other electrical feature comprises a conductive trace and an electronic component (212, 214) that is a mounted electronics component, and the at least one electrical feature and/or the at least one other electrical feature include light sources or light detectors, a plastic layer molded between the first and second substrate films so as to at least partially embed the electrical features on the first sides of both the first and the second substrate films within the plastic layer, wherein said electrical feature and said other electrical feature have been provided to the films prior to the molding, and wherein at least the one of the first and second substrate films comprising said conductive traces and said electronic component (212, 214) is thermoformed to a three-dimensional, non-planar, shape, the thermoforming being performed subsequent to providing said conductive traces and said electronic component (212, 214) on the film. a first substrate film configured to accommodate electrical features on at least first side thereof, said first substrate film having the first side and a substantially opposing second side, a second substrate film configured to accommodate electrical features on at least first side thereof, said second substrate film having the first side and a substantially opposing second side, the first sides of the first and second substrate films being configured to face each other, at least one electrical feature on the first side of the first substrate film, at least one other electrical feature on the first side of the second substrate film, wherein the at least one electrical feature or the at least one other electrical feature comprises a conductive trace and an electronic component (212, 214) that is a mounted electronics component, and the at least one electrical feature and/or the at least one other electrical feature include light sources or light detectors, a plastic layer molded between the first and second substrate films so as to at least partially embed the electrical features on the first sides of both the first and the second substrate films within the plastic layer, wherein said electrical feature and said other electrical feature have been provided to the films prior to the molding, and wherein at least the one of the first and second substrate films comprising said conductive traces and said electronic component (212, 214) is thermoformed to a three-dimensional, non-planar, shape, the thermoforming being performed subsequent to providing said conductive traces and said electronic component (212, 214) on the film.