@Wyt: Those models are amazing O.o
your detail is pretty close to that, except it's not that finished, yet
@BbB: the cast tool is very simple, as long as you have one-layered stuff.
As soon, as you have overlapping edges/faces (POV = center), and your aim is not to flatten it out, completely, you'll need to use vertex-groups.
And I didn't figure out the advanced settings of it, yet (with the definable radius, etc.)