Rigid plastic items are sturdy and self-supporting. They are formed in many ways. One common forming method is injection molding, where hot, molten plastic is forced into a mold under very high pressure, then removed as the die is cooled. An example of this is a butter tub or the common plastic bucket. Another common forming method is called blow molding, where a molten plastic tube is inflated with air (much like a balloon) to fill a mold, then removed when cool. An example of this is a milk jug. Vacuum forming takes a thin sheet of hot plastic, and using a vacuum draws the plastic into a shaped cavity.
Examples of this are very thin nursery tray inserts and folding clamshell packages. Bottles are blow molded items.
Bottles are blow molded items.
These are all injection molded items.
These plastics are vacuum formed.
Rigid plastics are made of several resin types, but in agriculture they are mainly high density polyethylene (HDPE, #2), polypropylene (PP, #5) and polystyrene (PS, #6). Common products are nursery pots, trays, flats, tray inserts, baskets and hangers, pails and barrels, to name a few.