Shape 1 Polymer Rib Blue FirmShape 1 Polymer Rib Blue Firm Shape 1 is our best seller. Not too big and not too small. It's just right. You need one in your toolbox really you do. The traditional kidney shaped rib is the most universally recognized pottery tool. It fits well in the hand and is useful for sculpting, hand building and throwing clay. All of our polymer ribs are made of unique flexible materials that are resistant to cracking and the formation of burrs. We've found