New ISO containers (McLaren Containers) are constructed with steel and marine-grade plywood flooring. Mostly, all shipping containers are made from steel and have closed-top with hinged doors. They have corrugated walls on the top and bottom sides and are welded to the rails and end frames. Steel is the main component that makes up a shipping container, but there are other components and materials as well that go into the building of them. Aluminium is also used, along with fibre-reinforced polymer. Or even a combination of all three materials.