this invention relates to a novel apparatus and process for producing thermoplastic articles . in one aspect , the invention pertains to a process for manufacturing fiberglass products using a fiberglass material consisting of fiberglass strands commingled with heat - formable polypropylene strands . a molding apparatus comprising : an air pressure chamber with an open side ; a flange plate fitted to the open side of the air pressure chamber , said flange plate having an opening therein for receiving a mold ; an upper bladder associated with the flange plate and covering the opening ; a base pressure plate ; a mold positioned on the base pressure plate ; and a locking mechanism for securing the air pressure chamber with the base pressure plate , and balanced air pressure in each chamber during molding .