an apparatus for molding plastic preforms into plastic containers may include at least one blow molding station having a cavity . within the cavity , the plastic preforms may be expanded into plastic containers . the blowing station has a bottom portion which delimits the cavity . the bottom portion is detachably disposed on a carrier by a fastening mechanism . the fastening mechanism has at least one pin - like body disposed on a first fastening element . the pin - like body engages in a condition in which the bottom portion is fastened to the carrier in a groove which is provided in a second fastening element . the pin - like body is displaceable relative to the carrier in the groove for fastening the bottom portion , and the groove is designed in such a way that an end section of the pin - like body may pass through the groove in a first section of the groove and cannot pass through the groove in a second section of the groove .