Each one contains about 150 million carbon nanotubes stacked vertically like trees in a forest. A carbon nanotube is an extraordinarily strong hollow cylinder about 1/50,000th the width of a human hair.
"Developments like this are an excellent way to bring the concepts of nanotechnology to a broader audience," said Hart, who made the portraits with his colleagues by working late on a Friday evening. "Also, we thought it would be fun."
The 3D likenesses are made of carbon and are half a millimeter wide. Link -Thanks, Sid Morrison!