I contacted the actor and explained to him what we are going to do to him. He agreed and then I took a alginate cast of him.

Here you can see the finished plaster cast..

I sculpted the nose in Roma Plastelina and made the edges as thin as possible. When sculpting you also have to look for undercuts so your moulds won't grip each other and won't come apart.
Common places for undercuts are the nostrils, base of the nose, lower lip and eyelids

Here the overflow edges are ready.
Note the round holes in the clay, these are called keys. If you have done keys in your mould
they will take pressure off your thin sculpted edges.

Now the clay walls are finished and I am ready to make a negative mould
of my sculpture.

To make the plaster contain as little bubbles as possible you gently pour the plaster down in the water and lets it soak for a while.
Then gently mix it with a spatula.

Spray a little silicone oil on your sculpture before you pour the plaster. Then you may gently tap the whole mould
against the table so all of the little air bubbles will come to the surface.

That's it!
The plaster has now set for an hour and the clay walls come off.

To open your mould
I usually use a screwdriver and gently pry it apart from the top of the mould
. This mould
came apart very easily, which means that I had found all of the undercuts and successfully eliminated them.

Here you can see me sitting and making the wig he will wear. I curled it with rollers, dried it and then dressed it.