since I got into Monster High webisodes and dolls I found a deviant art page that is quite unique.
The guy uses air-dry clay for the bellies.
The link is http://ninshinobi.deviantart.com/gallery/ the monster high dolls are on page 2.
What do you guys think?
Inflatingclothes.
Nice! The only fault I'd want to mention is the rough surfaces of the exposed bellies, but the dolls with clothed bellies look really sweet. The belly shapes vary from okay to good. Curiously, the older dolls with exposed bellies have smoother bellies. It looks like he got lazy. Belly shape is better in his newer work though.