Method of manufacturing at least one flexible plastic container, each container comprising two separate walls (12, 13) facing one another, joined on at least one part of the circumference thereof by a sealed peripheral edge, said separate walls defining a storage space of the container, characterised in that at least the following steps are carried out: d) using a single continuous film formed by extrusion by means of an extruder, producing a stack of two sheets (26, 27) of plastic material at the output of the extruder from said film thus obtained, said sheets (26, 27) being pressed against one another, the surfaces which face one another of these sheets (26, 27) being placed directly in contact with one another without any element acting as an interface, e) simultaneously shaping said sheets (26, 27) thus pressed against one another in order to define said at least one container without the previous separation thereof, at least each container being partially formed, said sheets (26, 27) being held pressed against one another in at least one part of the areas of said sheets (26, 27) intended to constitute said peripheral edge of each container during this shaping, said shaping being carried out by suction moulding by placing said stack between two mould parts which can be spaced apart from one another and brought to bear one against the other thus defining one or more cavities, at least one of these cavities thus formed corresponding to the shape and the external dimensions of a container to be manufactured, said at least one cavity then being closed at a portion of the periphery thereof corresponding to a portion of the peripheral edge of the corresponding container to be formed, at least one of said mould parts including a plurality of orifices connected to one or more pump units, f) at least partially sealing the areas of said sheets (26, 27) intended to constitute said peripheral edge of at least each container. d) using a single continuous film formed by extrusion by means of an extruder, producing a stack of two sheets (26, 27) of plastic material at the output of the extruder from said film thus obtained, said sheets (26, 27) being pressed against one another, the surfaces which face one another of these sheets (26, 27) being placed directly in contact with one another without any element acting as an interface, e) simultaneously shaping said sheets (26, 27) thus pressed against one another in order to define said at least one container without the previous separation thereof, at least each container being partially formed, said sheets (26, 27) being held pressed against one another in at least one part of the areas of said sheets (26, 27) intended to constitute said peripheral edge of each container during this shaping, said shaping being carried out by suction moulding by placing said stack between two mould parts which can be spaced apart from one another and brought to bear one against the other thus defining one or more cavities, at least one of these cavities thus formed corresponding to the shape and the external dimensions of a container to be manufactured, said at least one cavity then being closed at a portion of the periphery thereof corresponding to a portion of the peripheral edge of the corresponding container to be formed, at least one of said mould parts including a plurality of orifices connected to one or more pump units, f) at least partially sealing the areas of said sheets (26, 27) intended to constitute said peripheral edge of at least each container.