Abstract: An extruder head has inner, middle, and outer annular outlets centered on a common axis and immediately adjacent one another, a flow splitter on the axis, first and second inlets axially upstream in an axial flow direction of the splitter, and a third inlet between the splitter and the outlets. A tubular inner passage centered on the axis extends in the direction from the first inlet around the splitter to the outer outlet and a tubular middle passage centered on the axis extends axially in the direction from the second inlet around the splitter to the middle outlet. An outer passage having an upstream portion axially downstream of the splitter extends transversely of the axis. A tubular downstream portion also axially downstream of the splitter extends coaxially around the inner and middle passages from the upstream portion to the outer outlet.