That guy's images are 2D only,aren't they? I mean he doesn't use 3D elements,
but I might be wrong of course.
Anyway... could be hard to arrange the cubes like that,the skulls especially.
One would be better off sculpting/modeling the big chunk and then go from
there.(Sculptris is still free Bobby
)
But,in case you like to place several cubes better,think of the cubic noise.
Some of the TG cubes could be displaced with that noise.Then a bit of stretching
and warping maybe...