They work because they have a reasonably large base and a reasonable stable thing floating. The clock hands aren't stationary, let alone stable, and since clock

They work because they have a reasonably large base and a reasonable stable thing floating. The clock hands aren't stationary, let alone stable, and since clocks are generally flat in one dimension you have pretty limited space to play with. The only way I've thought of to make it work would be to have a fairly large "hub" at the center of the floating thing, with the two hands coming out off the floating hub. But that would be much less visually impressive, I think. The hub would have to be large enough that the movement of the hands is relatively miniscule in terms of weight distribution.