Yep, and there are other types of epoxies scultptors use...Procreate, is a grey product, Milliput a white one, and Brown Stuff....but for some reason they all get called 'GREENS'.
Most of the online mini stores sell it (or a variety of it). It takes some getting use to, and not only is it ideal for sculpting (because it holds under the pressure of metal and resin molding), but it's invaluable as a conversion materiel. Filling gaps, adding hair, texturing some fur, etc. etc.