Step Three – Produces a mold that is the negative of the original shape

This produces a mold that is the negative of the original shape and smooth on the inside. A rubber bladder (made using slosh molding) is shaped like a fuselage (or any other structure) and is covered with carbon-fiber preform, then placed inside the mold. The bladder could be made the same size as the plug, or slightly smaller. (In the prototype example shown, the rubber ball acted as the bladder.)