stabilization machines in which in the corresponding way as has been described previously they are pressed against the walls of the moulds in the temperature stabilization machines by means of an overpressure at an appropriate temperature and during the time required it will hereby be found that the invention can be applied to existing machinery utilizing its maximum production capacity the temperature stabilizaton is thereafter carried out in separate equipment and the capacity of this equipment can then be adapted to the capacity of the existing machinery the description given above of an embodiment of the invention is only to be regarded as one example of an embodiment trials have shown that it has been easy to adapt machines of various types known and used to meet the special temperature requirements indicated for the method of producing containers according to the invention as previously mentioned the above mentioned temperature data refer to the polyester akzo arnite for other crystallizable thermoplastic polymer plastics suitable for use in the manufacture of containers of the kind herein foreseen other temperatures may have to be applied these embodiments are also included in the concept of the invention as a variation of the temperatures in relation to what has been stated above merely involves the utilization of the materials used within the corresponding property ranges as those indicated.