### Instruction: From the passage list down the materials used to prepare boomerang. List the results in comma separated format.
### Input: A boomerang is a throwing stick with aerodynamic properties, traditionally made of wood, but also of bone, horn, tusks and even iron. Modern boomerangs used for sport may be made from plywood or plastics such as ABS, polypropylene, phenolic paper, or carbon fibre-reinforced plastics.

Boomerangs come in many shapes and sizes depending on their geographic or tribal origins and intended function. Many people think only of the traditional Australian type, although today there are many types of more easily usable boomerangs, such as the cross-stick, the pinwheel, the tumble-stick, the Boomabird, and many other less common types.

An important distinction should be made between returning boomerangs and non-returning boomerangs:

Returning boomerangs fly, and are examples of the earliest heavier-than-air human-made flight. A returning boomerang has two or more aerofoil section wings arranged so that when spinning they create unbalanced aerodynamic forces that curve its path into an ellipse, returning to its point of origin when thrown correctly. Their typical L-shape makes them the most recognisable form of boomerang. Although used primarily for leisure or recreation, returning boomerangs are also used to decoy birds of prey, thrown above the long grass to frighten game birds into flight and into waiting nets. Non-traditional, modern, competition boomerangs come in many shapes, sizes and materials.
Non-returning boomerangs, throwing sticks, valari, or kylies, are primarily used as weapons. They lack the aerofoil sections, are generally heavier and designed to travel as straight and forcefully as possible to the target to bring down game. The Tamil valari variant, of ancient origin and mentioned in the Tamil Sangam literature "Purananuru", was one of these. The usual form of the Valari is two limbs set at an angle; one thin and tapering, the other rounded as a handle. Although valaris come in many shapes and sizes they are usually made of cast iron cast from moulds. However, some may have wooden limbs tipped with iron or with lethally sharpened edges or with special double-edged and razor-sharp daggers known as kattari.
### Response: wood, bone, horn, tusks, iron, plywood, plastics such as ABS, polypropylene, phenolic paper, carbon fibre-reinforced plastics