IBM 3D Prints World's Smallest Magazine Cover
National Geographic Kid's nano-printed cover is small enough to fit on a grain of salt -- 2,000 times. The gray-scale duplication of NatGeo Kids' cover is actually invisible to the naked eye. Dr. Colin Rawlings, a physicist at IBM Research, said that even with a microscope, you'd only be able to make our a blurry image. To see it in full, you need an electron microscope.