hey soap makers!

[tinfoiledgrrl.livejournal.com]

I have a quick question. I am trying to create those large bricks of soap that you slice (almost like a loaf of bread) with an interesting design made of other soap inside. I have seen sailboats and all kinds of stuff crafted inside these soaps at different shops around town, but I can't figure out how to create what I am looking for (a communist shape, for a friend of mine) I figure that it should be made with glycerine soap, but if I am wrong let me know. Anyways, after all that, I guess my question is, how do i do this? Do I have to carve shape and then embed it like normal, or is there an easier way?