Plastic compounding is a way to enhance plastic for use in products. The process is done by a company called a "plastic compounder" who mixes plastic like a "chef" would mix ingredients. Engineers at the plastic compounding company mix plastic formulations by mixing or/and blending polymers and additives by heating them up until they "flow" in a molten state. Machines called co-kneaders and twin screws (co- and counter rotating) as well internal mixers are the most common used compounders in the plastic industry.
This is one example of a specialty plastic that is created using the compounding plastic.