THIS QUESTION IS ALREADY ANSWERED!
I've received so many wonderful tips and helpful advice, all my questions have been ansewered several times over. Thank you so much for all you help!
As you can see in my gallery, I like to do highly detailed, about hand-sized figurines. I like the slick smoothness of real clay, but there's the shrinking ploblem. What I'm using at the moment is a lightwight, air-hardening substance called EfaPlast that is quite cheap. The problem with this Material is that it never gets all that hard in the first place and that it is resoluable with water. Which is fine when you want to correct things, but not so fine when my water-based acryllics soak the material through and then trap the water within when they're dry.
So I'd like to ask what you think about other brands of sculpting material. It should be easy to use (I'm not very patient and I don't work neat and tidy) and not too expensive. It would also need to be something that I can get my hands on here in Europe without paying a fortune for shipping and waiting half a year for it to be delivered.