A sealing strip, such as for fitting to the frame of a door opening in a motor vehicle body, comprises a longitudinally extending channel-shaped mounting portion incorporating a channel-shaped reinforcing carrier. The method comprises the steps of providing a workpiece comprising a layer of material suitable for the wave guide strip; patterning the layer so that the workpiece comprises, a base portion and the at least one protruding portion; forming a cladding layer on the protruding portion; and attaching the cladding layer to a substrate. A recess is formed in the bore at the end of each of the tubular members.