A thermoplastic pre-container, typically a blow molded piece, is provided to form several hollow bodies. The pre-container is elongated along a central axis and includes a bottom section, an opened section and in-between at least one hollow body section. A plurality of circumferential grooves are provided in a pre-container sidewall, each with a bottom line formed in a virtual plane perpendicular to the axis. The bodies are obtained after cutting the pre-container in a direction transverse to the central axis and severing the end sections. Due to the cutting at several of the circumferential grooves, a top opening and a base opening are respectively obtained for at least two hollow bodies, each opening being delimited by an annular inner rim of a body flange.