Scientists at Disney Research in Pittsburgh have developed a process to 3D print electrostatic speakers in a way which allows them to create speakers which produce sound in all directions, and can be created in any shape they desire.
http://3dprint.com/2846/disney-3d-printed-speakers/
Such speakers could be used within toys and games to provide ultrasonic sound for tracking, or just to produce sounds in small areas which would not have been able to hold a speaker made any other way. They are currently looking for ways to print the speakers in one piece, not needing to rely on other methods of manufacturing combined with 3D printing. Watch the video below for more details: