Imagine tiny structures like scallops or amoebae could be created which travel down blood vessels in search of blockages or tumors. It might not be far off as a team of researchers at the Max Planck Institute for Intelligent Systems have used 3D printing to create a “micro-scallop” of sub-millimeter size which might allow noninvasive exploration inside the human body. The "scallops" are single-hinge, “micro-swimmers” that move much like the scallop described by a former Nobel Prize winner, and they were made from polydimethylsiloxane (PDMS), loaded with phosphorescent pigment and then cast into a 3D printed mold. If you want to read more about this technology, you can see it here: http://3dprint.com/30235/3d-printed-micro-scallops/