Craft Porcelain by AMACO is a non-toxic, air-dry modeling material that some say is similar to cold porcelain. According to the manufacturer's description,
Craft Porcelain is ideal for creating flowers, floral decorations, figurines, and other sculptures; dries in 24 hours and has a porcelain-like finish that can be further decorated with oil or acrylic based paints.
Craft Porcelain is currently available in white* plus 6 colors, however, I've heard the colors are being discontinued.