Preferably, prior to insertion into the blow mold cavity 18, an unblown uniaxially longitudinally oriented preform 44 of polyethylene terephthalate is heated to the appropriate stretch temperature of between about 190??? F. to about 265??? F. It will be appreciated that preform 44 may not be of the shape shown in FIG. 1 and that suitable materials other than PET, as disclosed herein, may be used.