Below is a list of Injection Molded Plastics manufacturers from Ontario, California. Injection Molded Plastic is resin that has been heated until molten and then forced into a pre-made mold or cavity in the shape of the intended plastic product or object. When the melted plastic has cooled and hardened, the mold is removed to reveal a hard, plastic part in the shape of the mold cavity. Products made from plastic injection molding, or custom injection molding, include a wide range of everyday household items such as mop buckets, plastic containers, screw driver handles and even video game cartridges.