A method for forming a lead or lead extension includes forming an arrangement of elongated conductors. Each of the conductors extends from a proximal end of the arrangement to a distal end of the arrangement. Each of the conductors includes a layer of insulation disposed over a conductive core. A conductor-separating element is disposed over either the proximal end or the distal end of the arrangement. The conductor-separating element includes a plurality of ablation windows defined in a body. An end of at least one of the elongated conductors is radially extended over a portion of the conductor-separating element such that a portion of the at least one elongated conductor extends across at least one of the ablation windows. Insulation from the portion of the at least one conductor extending across the ablation window is ablated to expose a portion of the conductive core of the elongated conductor.
