The method involves realizing a forming die presenting complex configuration and realizing a membrane (1) made of expanded polytetrafluoroethylene, where the membrane has fibers (3) that does not present preferential orientation. The membrane is heated till temperature higher than a gel point of the polytetrafluoroethylene and is applied against the die using a pressure difference created between two sides of the membrane to conform the membrane to configuration of a hemocompatible object. The membrane is cooled by maintaining the membrane on the die and the membrane is released from the die.