Abstract: A method of making a disposable tumbler includes: injection molding a polyethylene terephthalate resin in an annular mold cavity defined by an injection mold wall and a core to form a resinous parison on the core; separating the parison from the injection mold wall by moving the parison on the core away from the mold wall; moving the parison on the core into alignment with a blow-mold; and expanding the parison by directing a pressurized fluid to its interior such that the parison separates from the core and expands to the surface of the blow mold to form the tumbler, wherein the parison is radially expanded by a factor of at least about 2.6 at its base to form the tumbler. Typically, the parison is radially expanded at its base by a factor of from about 2.6 to about 3.25 to form the tumbler; whereas preferably the parison is expanded by a factor of from about 2.7 to about 2.9.