PET preforms/bottles are traditionally manufactured either by One-Step "hot preform" method or Two-Step "cold preform" method.

One-Step "hot preform" method
In this method all processes are completed on one integrated machine. The injection-molded preform is withdrawn from the injection cavity while still hot enough to be stretch blown to form the bottle. No extra heating is required, and since preforms are not stockpiled to be blown at a later date, but are freshly molded every time, there is no risk of surface damage from preforms knocking together during storage or transportation. One-Step method is highly suited to small and medium scale production lines.

Two-Step "cold preform" method
The preform is injection molded on the first, then reheated and blown on the second. The Two-Step system uses two separate machines: an injection molding machine for making the preforms and a reheat blow molding machine to reheat the preforms from cold and blow the bottles. The requirement for a preform heating system means the Two-Step process has a lower thermal efficiency. This method is most suited to medium to large-scale production.