A method comprises forming a preform of plastic material, expanding said preform to obtain a container, said forming comprising compression-forming said preform in that mould arrangement wherein said expanding occurs; a method comprises expanding a preform in a mould arrangement to obtain a container, before said expanding it being provided to form a dose of plastic material in a paste state in said mould arrangement to obtain said preform; an apparatus comprises a forming mould arrangement, a punch device for expanding a preform in said mould arrangement, an abutting device cooperating with said punch device, said punch device and said abutting device identifying a configuration in which said punch device and said abutting device cooperate to define a forming unit for compression-forming a semifinished product of plastic material to obtain said preform and a further configuration in which said punch device and said abutting device cooperate to define an expansion unit of said preform to obtain a container.