The invention relates to an arrangement in connection with extrusion tools. It comprises a nozzle structure which is provided with coaxially arranged nozzle elements (1, 2, 3, 4) and is arranged to form one or more layers which cover a flexible elongated element (6) on the surface of the flexible elongated element (3), which passes through the innermost nozzle element (4), and a guide member (5) corresponding the diameter of the elongated element (6) for controlling the flexible elongated element (6). The guide member (5) is arranged to be pushed in the direction of the elongated element (6) into its position inside the two innermost nozzle elements (3, 4) defining a first melt channel (7). The guide member (5) is arranged to provide a tapered space (52) between the elongated element (6) and the guide member (5), and the tapered space (52) is in fluid communication with the first melt channel (7).