Reusing
Reusing  is taking a material or  an object with one use  and changing it into an  object with a different use.

An example would be to take an empty cereal box, which is made from boxboard, and make it into a cubic decimeter
.

The advantage is that when the project  does not have any furthur use, you can recycle it. You will save money,  learn a lot and it is great for the environment!
This student reused old cd's to make wheels for his gravity car.