A method of fabricating a dual-chamber plastic container in an injection/extrusion/blow-molding operation, in which a container finish is first injection molded. The finish mold tooling is then moved axially upwardly as plastic continues to be extruded through extrusion tooling in which an orifice bushing surrounds a mandrel tip. The mandrel tip has a passage through which plastic is extruded to form a wall that divides the extruded tube into separate chambers. Blow molds are brought in from both sides to capture the extruded tube, and air is blown through a passage in the finish mold tooling to blow the tube chambers to the confines of the mold.