An apparatus for the manufacture of selectively apertured thermoplastic sheet or film, comprising a rotatable molding element means for receiving the film and which means has a predetermined pattern therein wherein as the film is contacted with the rotatable molding element means and a fluid pressure...http://www.google.de/patents/US4644623?utm_source=gb-gplus-sharePatent US4644623 - Method of making a rotatable molding element for selectively aperturing thermoplastic film
