Abstract: An extruder head has an inner die member (5) housed in a supporting body (2) and provided with a central duct (6) continuously passed through by a semifinished product (7). An outer die member (9) exhibits a shaped housing (10) defining, in cooperation with the inner die member (5), an outflow port (11) for the mixture to be applied to the semifinished product (7). The shaped housing (10) is defined in a centering element (12) rotatably housed, according to an oblique and incident axis relative to the axis of the central duct (6), within an intermediate collar (13) rotating in the supporting body (2) in coaxial relation with the central duct itself. By rotating the centering element (12), the outflow port (11) moves from a centered position to a maximum-eccentricity position with respect to the central duct (6). The rotation of the intermediate collar (13) modifies the orientation of the common plane containing the axes of the outflow port (11) and central duct (6).