Ok, I sculpted a clay creature and now plan to make a plaster mold for it. The plan is to make a clay sculpt, then make a two part plaster mold of it. Once the mold is made, I will clean out the clay (destroying the sculpt in the process) and put the two halves back together. I then plan to pour some latex (mold builder) in the mold, swish it around, then pour out the excess. I will let that dry, then repeat a few times until the latex skin is thick enough.
Then I plan to pop open the mold, and have a great latex skin of my sculpt. I will cut maybe between the legs so I can slide a metal armature inside, and then fill it out with some cushion foam (like from a seat cushion) to form the muscles.
I will post more as it progresses. These pictures are the torso only. I will sculpt the limbs and head separately. The sculpt right now is about 5″ high. I started with a lump of clay around a pencil which is held upright with a hole in a piece of scrap wood. The creature is a big scaly creature with leather straps holding on a quiver of arrows.