Machine for forming containers (10b) made of thermoplastic material by blow-moulding preforms (10a) obtained by means of injection/moulding within the machine, for which at least one longitudinal direction (X-X) for feeding of the preforms (10a) between the stations thereof is defined, said machine comprising: - an injection unit (100) provided with a longitudinal injector (101); - a station (200) for moulding the preforms (10a), comprising a mould (203,206) with a predefined number of cavities for injection/moulding of preforms (10a); - a station (300) for blowing the preforms (10a), comprising a blowing assembly (310,320) for forming finished containers (10b); said blowing assembly (310,320) comprising a smaller number of blowing cavities (321c) than the number of injection/moulding cavities in the mould (203,206) and being displaceable in both senses of the longitudinal direction (X-X) on fixed longitudinal guides (301;1301).