Thermoforming is a simple to understand process which involves creating a plastics mould by heating a thin plastic sheet until it is malleable, and trimming away excess material.  Thermoforming is commonly used to make very thin consumer products such as clam shells and blisters for pills. However, when this same technology is applied to thicker sheets in the 1/4" range, it can be used to make products such as shipping trays for motor components and aerospace parts.