I am about to cast a wax sculpture that took a long time to make. because of my fear that it will not turn out I duplicated the head in wax. Here is the original Wrapping the head in Amazing mold putty. I only did the head because this stuff is not cheap. It is a very easy way to make copies of just about anything though. It is like two tubes of silly putty like substances that you mix. After it sets i cut the back of the mold with a razor.
Here is the mold being filled with wax. I melted microcrystaline wax in a can sitting in boiling water. The back of the mold is held shut by the can.
The completed head not a perfect replica (lost an ear). but enough that i can work from if I need to.