Existing 3D printers of resinous materials, whether cured by light or air, require layering. Layering takes time; in his video on making molds for designer edibles, for instance, Eric Strebel pointed out that each print took 24 hours.
Seeking to speed the 3D printing process, a team of researchers at UC Berkeley have developed a new method: Computed Axial Lithography. By filling a cylinder with light-curable liquid resin, then rotating it while hitting it with a “dynamically evolving light pattern,” they are able to cure the object in spins (perhaps a single spin?) rather than layers:
The technology is still in its nascent stages, and right now they can only print objects on the centimeter scale (though with speedy build times of 30 seconds to two minutes). Presumably the scale will increase. And they mention a rather interesting possibility in their research paper: “Our process enables us to construct components that encase other pre-existing solid objects, allowing for multi-material fabrication.”