The pattern can be reused almost indefinitely to create more molds in additional casting flasks.

Air-set molds are often formed with the help of a casting flask having a top and bottom part, termed the cope and drag.

In foundry work, the terms cope and drag refer respectively to the upper and lower parts of a two-part casting flask, used in sand casting.

The model, called a pattern, is then placed in a casting flask, in its simplest form a topless and bottomless box split in half around its perimeter.

The model is made of polystyrene foam, which is placed into a casting flask, consisting of a cope and drag, which is then filled with casting sand.

A multi-part molding box (known as a casting flask, the top and bottom halves of which are known respectively as the cope and drag) is prepared to receive the pattern.

When casting with metals like iron or lead, which are significantly heavier than the casting sand, the casting flask is often covered with a heavy plate to prevent a problem known as floating the mold.