an extrusion blow molding apparatus for making hollow plastic articles includes a machine frame with an extruder horizontally received in the machine frame and having a nozzle head for vertically extruding a parison at one end face of the machine frame . a pair of split blow molds is disposed at this end face of the machine frame bilaterally underneath the nozzle head , with each blow mold cooperating with a blow mandrel secured to the machine frame above the blow mold . the extruder together with its drive and supply lines and at least one of the blow mandrels are detachably received in the machine frame so as to allow a positional exchange therebetween for allowing blow molding of round plastic articles as well as flat plastic articles .