Blow moulding is used to design hollow plastic parts such as bottles and hollow plastic shapes. Blow moulding is done by a special structure called Parison which is made up of plastic caller thermosetting plastic. The parison is a tube like plastic structure with a hole on one end that air can pass through it. In first step the plastic is melt and passed into the parison. The parison is clamped to the mould with the desired shape by passing the air through the parison. The air pushes the plastic out the parison against the mould. The mould is cooled to obtain the specific shape of the plastic. An early stage of the blow moulding uses glasses. Since the glasses are easily breakable modern techniques are replaced with plastics. Some of the components produced by blow moulding include Industrial bulk containers, Lawn, garden and household items, Medical supplies and parts, toys, Building industry products, Automotive-under the hood parts, Automotive-under the hood parts, Appliance components. The cost of blow moulding is less compared with other moulding design techniques.