wow thats fantastic!! and looks totally do-able Am guessing the 'swirl' stuff just has alot more shaving foam, whereas 'marbled' just mixes colours with alot less white. You could also pre-dye in a base colour if you wanted as well.
I've just done a couple of testers, and it's official, you can't do it with dylon easily, you can't get the consistency quite right, though thats me someone else may have a knack for it! I didn't get the quantities quite right but it turned out ok, will post pics in a mo, but my camera is dead so I'll have to take them on my phone!