4D Printing Adapts

So what is 4D Printing?  Printing objects that can adapt to their environment.  In GigaOM.  " ... 3D printing promises to give us objects on demand. But 4D printing promises to give us objects that change over time, adapting to new situations and needs. ... An $855,000 grant from the United States Army Research Office is enabling researchers from three universities to develop materials capable of changing after they are 3D printed. For example, an outfit printed for a soldier could change to a camouflage print or adjust to be resistant to shrapnel. ... "