Grand Illusions shows us what you can do with pyrolytic graphite and four 12mm neodymium magnets. Video demonstration after the jump.
The floating square is pyrolytic graphite, which is extremely diamagnetic. In effect it is a single crystal of graphite, and because the resulting graphite is very highly ordered, pyrolytic graphite is extremely diamagnetic. Also the density of pyrolytic graphite is fairly low. The combination of these two factors – the low density and the strong diamagnetic effect – makes this amazing demonstration possible