a system for transforming plastic parisons to plastic containers with a transport device which transports the plastic parisons along a predetermined transport path , wherein the transport device has a movable station support disposed at least indirectly on a stationary base support on which a plurality of transforming stations is disposed . the transforming stations each have blow mold devices which each form cavities within which the plastic parisons can be transformed into the plastic containers and these blow mold devices are each disposed on blow mold supports . the system has a changing device which is suitable and intended in order , in a changing mode of the system , at least to remove the blow mold devices from their blow mold supports and / or to dispose blow mold devices on the blow mold supports , and wherein , during a further mode of operation which differs from the changing mode , this changing device is suitable and intended for carrying out a treatment operation on at least one working element intended for the system .