How can I go about making my own fashion doll molds?

I am interested in making my own 12" fashion doll because the really good ones that are for sale are SO EXPENSIVE. Does anyone know how can I go about making my own fashion doll molds using plastic, rubber or other materials? I am not interested in transforming a doll that is already made, but starting from scratch. Serious replies only. Thanks.

You will have to make an original model. One method is to work with never hardening soft modeling oil clay (plasticine) when you have a version you like, you paint it with many layers of latex molding material (or use expensive RTV silicone molding rubber), back the soft mold with plaster and peel off the rubber from the clay carefully. If you wish, you can keep the keep the model and modify and rework it to make a different version without building the whole thing from scratch (like different head shape, bustier or flatter, etc. but legs, waist, shoulder, arms not changed.)

If you are going to make a figure with movable arms and legs it get more complicated as you will model each of those separately and have to model the front and the back and cast in separate pieces so you can fasten the arms and legs (and head?) with elastic.

Once the mold is made, you then can cast in tough casting wax for your own use, or get involved in clear and opaque casting resins.

For examples of the first part of the process see

http://users.ticnet.com/mikefirth/castgobl.htm#HDFTGOB

I don't do resin casting, so you will have to explore for the second part.

http://www.alumilite.com/ looks promising on a quick Google search