Blow mould making process involves four operations: A two-part die is opened and a heated length of thermoplastic tubing is either drawn onto or extruded over an air pipe placed between the two halves of the open die, the die halves are then closed and, in so doing nips shut the open end of the parison, air is next blown into the parison, and this expands the plastic tube out to the walls of the die, which are usually water cooled to cool the plastic down as quickly as possible, and so minimize cycle time, finally, the die is opened to allow the component to be ejected. This forming process is easily mechanized, and is often integrated with an extrusion machine that is producing a continuous supply of tubing. It is useful for the high-speed production of bottle-shaped components, from everyday small flexible bottles to large-capacity drums.