Researchers at TU Delft have combined origami techniques and 3-D printing to create flat structures that can fold themselves into 3-D structures like tulips. The structures self-fold according to a pre-planned sequence, with some parts folding sooner than others. Usually, expensive printers and special materials are needed to fabricate such objects. But the TU Delft scientists have created a new technique that requires only a common 3-D printer and ubiquitous material. Among other applications, their research has the potential to greatly improve bone implants.