Plastic forming is a process which takes place when a sheet of plastic is heated in an oven for enough time to yield (material becomes soft). At that exact instant, the plastic sheet is brought on top of a male or female mold where a high vacuum process is activated.
This process is called thermoforming and it allows the plastic to form around the cavity or the shape on the given mold. Once the forming cycle is completed, four overhead fans expedite the cooling of the formed part. When the plastic solidified (rigid), then this mold gets extracted and the part is formed.