You might wonder about self assembly that all the nanos are talking about. Here's a photo of marbles that have been pushed together on a flat surface. As one might expect, the marbles settle in to the most compact form for spheres (or circles on a 2D surface).
Notice that every marble has six other marbles surrounding it. Since they are all the same size, which is very important, the marbles will always group into this basic hexagonal pattern. All circles, spheres, golfballs, carbon atoms want to do this.
The rules at the atomic scale however, are a little different. Here the hexagon is ruled by the physical contact to the mutually spherical surfaces of these relatively large, atomically speaking, glass spheres. With atoms, the charges and electron bond arrangements rule. Carbon atoms bond to lots of things including other carbon atoms, and can do so "at many places around their surface" if you could call it that. Being an atom is not like being marble, and the surface of an atom, or shell, is apparently comprised of orbiting subatomic particles called electrons.
Have you ever seen a marble made of marble? I have not, but I'm sure they exist and go back at least as far as the Classical Greek period and probably much earlier. Today, marbles are produced en-masse in marble making machines that spit out little dollops of red hot glass.
Gee whiz, that got me looking around for some marbles of antiquity - instead I came up with this informative site all about marbles. Cool.