Polymers give more design freedom than metals. The elastic
hinge is one example of this, reducing the box, hinge, and lid (three components
plus the fasteners needed to join them) to a single box-hinge-lid unit,molded in one operation. Their spring-like properties allow snap-together,easily joined parts. Another example is the elastomeric coupling—a flexible
universal joint, allowing high angular, parallel, and axial flexibility with good
shock absorption characteristics. Elastomeric hinges offer many opportunities
to be exploited in engineering design.