shuttle blow molding apparatus having an extruder or a blow head for substantially continuously emitting a thermoplastic material in tubular or parison form at a moldable temperature downwardly along a vertical axis . a finite length of the thermoplastic material is grasped by a first mold set , which then moves downwardly with respect to the extruder or blow head to provide clearance for a second mold set to move to a position to grasp a second finite length of the emitted thermoplastic . the first mold set is then moved horizontally away to permit the emitted thermoplastic length therein to be blown into a hollow article , and thereafter removed from the first mold set that is permitted to return and engage an other finite length of the thermoplastic material . the second mold set follows the first mold set in a path of travel traced by the first mold set . a single in - mold labelling device can be provided to sequentially apply labels to the interior of the mold sets , while the mold sets are open , for application to the articles being blown in the mold sets .