I made this a while back for a custom toy show. It is from a white blank My Little Pony. I pulled the mane and tail and used a wire support for the tail. I sculpted directly on the pony using sculpey. A common technique to "baking" the clay on the figures is to boil the entire pony to harden the clay. This worked well. After some light sanding to blend any seems, I airbrushed the base green and did the details by hand. I used acrylic paint.
Painting in progress.
During the sculpt process.
In case anyone's interested I included the links to two of my past custom toy projects.
Another Custom My Little Pony
Custom Hello Kitty