Fix-it sculpt is fantastic, but it is not quite as pliable as Greenstuff. It bonds well, and it dries hard. I would not call it brittle, but it has no give in it, so thinner pieces will snap if you put too much pressure on them. I also find it is much easier to work with than Greenstuff in terms of sculpting, carving, putting line in it while it's still in the workable stages. They also sell a solvent you can put on your tools that won't get caught in the soft stuff and make cuts and sculpts smoother.