Many processing plants have equipment to "blow mold" their own plastic milk bottles. Plastic pellets are heated to over 300 degrees. Then, "blow mold" machines create molten plastic "balloons" that are encased by the two halves of the mold. After a few seconds of pressure, out comes a gallon plastic jug! Another machine trims all the excess from the container and then sends that scrap material around to be re-used by combining it with the raw material pellets.

The half-gallon jugs come out of the molds a little larger than they should be. So, they are sent through an "annealer" where they are briefly subjected to 1100-degree heat. That's enough to shrink them to the proper size.

Overhead conveyor systems move the containers along to the next step in the process.