Abstract: On the-inside of heated molds hollow bodies are formed by vulcanization, the bodies are formed of elements from natural or synthetic rubber and/or treated elastomers, possibly associated with different materials such as leather, skin, cotton, metals, expanded rubbers and others, combined with each other. A pressurized fluid, such as hot or cold air, vapor or compatible gas, is injected between the hollow bodies being formed. During vulcanization, the components, airtight-coupled with each other along at least a contact and sealing common line, are pushed and kept in forming adhesion against the mold surfaces by the pressurized fluid.