what clay do u use for your sculptures?

To all you wonderful sculptors out there (and you know who u are!), what clay do u use for your works? I use Apoxie. I do not sculpt custom animals but I do use it to put them in different poses or make one animal into another. Also, where do people go for animal sculpting classes? I can not to find any around Boston in the states, but I wonder if that subject (animal sculpting) is too narrow of a focus. Any suggests welcomed!

Thanks, Seanie

I use Super Sculpey Firm an oven cured clay