Are there any durable sculpting materials that have some flexibility once cured? I currently use Apoxie Sculpt and it works really well but it's very rigid and brittle. For most things I do, that's fine, but sometimes I want to make a part that's thin and I'd like it to have at least a little flex before it breaks. Basically the closer it can be to plastic, the better. The only other materials I'm aware of are Green Stuff and Milliput. I seem to recall being told that one of those has more flexibility than apoxie but I can't remember which. Whatever I end up using also needs to be able to be sanded and take paint well. Bonus points if it's less sticky while working than apoxie is (one of the biggest challenges I have with apoxie sculpt is keeping it from sticking to my fingers while I work).