method and apparatus for the continuous extrusion of rods of plastic raw material . the rods contain at least one inner channel which is at least in part spiral - shaped . the raw material may be a powder - metallurgical or ceramic mass . the material is extruded through a nozzle mouthpiece and made to rotate by an arrangement of flow guiding surfaces . at least one thread made of a flexible or elastic material is entrained and gives the rod a spiral shape with a predetermined pitch . the thread is retained upstream of the nozzle mouthpiece in an eccentric position relative to the rod axis that extends through the nozzle mouthpiece . the movement of rotation of the raw material is adjusted by an outer adjusting force which modifies the angle between the arrangement of flow guiding surfaces and the longitudinal axis of the nozzle mouthpiece to adjust the position and pitch of the spiral channel .