There is a tendency to utilize underground space for the less ornamental purposes of civilization; there is the Metropolitan Railway in London, for instance, there are new electric railways, there are subways, there are underground workrooms and restaurants, and they increase and multiply.
Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and CD and DVD cases), containers (such as clamshells), lids, bottles, trays, tumblers, and disposable cutlery.
Each form of returnable packaging is made of materials such as plastics, injection molding, textile-based protective packaging and other materials that are durable and designed for multiple uses. The main use is to safely move materials or products. This type of packaging can be used internally to move product from one process to another or to different areas of the plant for storage or future processing. Returnable packaging can also be used to move product between vendors with different processing specialties.