A mounting structure for installation at a corporeal port opening. The mounting structure includes a reentrant tube on an exterior surface of which is disposed at least one balloon, with a proximal everted portion of the tubing extending from the distal portion of the tubing, with a gas flow passage associated with the tubing, for selective inflation of the balloon. A vacuum thermoforming process for making such mounting structure is described. The mounting structure is useful employed for anchoring of a therapeutic device such as an ostomy bag at a corresponding port of the body, with the balloon(s) of the device providing effective anchoring of the mounting structure and permitting the mounting structure to be comfortably worn by a patient during therapeutic intervention.