A semi-rigid heated element assembly and method of manufacturing semi-rigid heated element assemblies is provided. A heated element assembly includes a first thermoplastic sheet, a second thermoplastic sheet, and a resistance heating element laminated between the first and second thermoplastic sheets. The resistance heating element includes a supporting substrate having a first surface thereon and an electrical resistance heating material forming a predetermined circuit path having a pair of terminal end portions. The circuit path continues onto at least one flap portion that is capable of rotating about a first axis of rotation. The reformable continuous element structure may be formed into a final element assembly configuration whereby at least the flap portion is rotated along its axis of rotation to provide resistance heating in at least two planes. Semi-rigid heating elements may be formed into heated containers, heated bags, and other objects with complex heat planes.