a method is disclosed for fabricating in a single stage hollow polymeric article of manufacture from a flexible fibrous material , regardless of the degree of complexity of the laminate . the material is applied to a hollow flexible envelope which includes a pattern of any degree of complexity and which is supported on a solid mandrel , to be encased in a two - part female die . the envelope and applied material are sealed off from the mandrel by means of film layers forming a bag . a vacuum is established within the bag , resulting in forces acting from the inner side of the envelope through it and the laminated material against the die walls . the support mandrel is removed , and the remaining assembly is cured under the vacuum with or without elevated pressures . after cooling , the die and envelope are readily removed from the article . the apparatus comprises the envelope , the support mandrel , impermeable sealing film for bagging the laminate , the tooling such as a female die or caul plates , means for establishing a vacuum on the bagged laminate and tooling , and optionally , means for turning the envelope and mandrel as the material is applied to the envelope pattern .