Use the adjective tensile to describe materials that can be shaped, such as the tensile clay that a potter crafts into a bowl or vase.
Tensile rhymes with "pencil." It might remind you of the word tense, and in fact, tensile can also mean "having to do with tension." Think about a tensile material, like wire. It will stretch and stretch until it reaches its limit. Drawn tight, with no slack, the wire has tensile stress.