the present invention comprises an extrusion arrangement for the controlled compounding and mixing of a plurality of time , pressure and condition sensitive substances in a single screw plastic extrusion machine , having a main support shaft connected to the downstream end of a single screw plastic extrusion machine , the support shaft enclosed within a barrel shaped housing , at least one stator and one rotor being disposed about the support shaft within the barrel shaped housing , and at least one satellite extrusion feeder arranged to supply an additive to the barrel shaped enclosure through an introduction port , the introduction port arranged at a location radially adjacent a rotor on its support shaft .