We've written about 4D printing before, but the objects printed by researchers at the Georgia Institute of Technology, Singapore University of Technology and Design, and Xi'an Jiaotong University are a little bit different from most of the other 4D printed objects we've seen before. The researchers at the three institutions created their shape-shifting objects by 3D printing them from multiple reactive materials, each designed to respond differently to a heat stimulus. Read more at 3DPrint.com: http://3dprint.com/171053/shape-shif...ects-4d-print/