A research team from the Georgia Institute of Technology and the Singapore University of Technology and Design developed a new 4D process that demonstrated complex self-folding structures. The structures were 3D printed with combinations of smart Shape Memory Polymers that would allow complex shapes to self-assemble when exposed to a single source of heat. Previous 4D concepts could create complicated shapes and movements but required multiple sources of heat applied at specific intervals. You can read more about this process over on 3DPrint.com: http://3dprint.com/96864/4d-smart-memory-materials/