Since i was in high school, i always use a reusable oil based clay in making my anime characters. Of course, figures made from oil based clay can't last long and easily gets deformed..
i also tried using plaster of paris and its a failure..
Then i tried using polymer clay..( if you want to know more about polymer clays, try visiting this site: garieinternational clayshop) and for my first attempt, i did Mai ,Shiranui from the king of fighters. can't remember exactly when but i did her probably more than four years ago...sooo far...
for my personal observations,, i need to work on detailing, proportions, better posture..and..many more... XD