3D Printing is already moving to its next phase where it will be possible to create complex structures that are required to move in their environment with high degrees of flexibility and durable characteristics.
Here Cornell University demonstrate how a simple loud speaker for an MP3 player can be manufactured using a 3D printer. It is quite a challenge given the speaker consists of a plastic housing, conductive coil and a magnet.
The impact on industry when such techniques are perfected for combining materials into fully functioning active (dynamic) systems will be enormous. Such items are of relatively high value given they are typically expensive to manufacture and especially so if they are only needed in small quantities.
Producing parts which are elastic for example is extremely difficult. However, if additive manufacturing is to be adopted widely for engineering purposes then 3D printers with such capabilities are going to be needed.