Marbles were originally made by hand. Stone or ivory marbles can be fashioned by grinding. Clay, pottery, ceramic, or porcelain marbles can be made by rolling the material into a ball, and then letting dry, or firing, and then can be left natural, painted, or glazed. Clay marbles, also known as "crock marbles" or "commies" ("common"), are made of slightly porous clay, traditionally from local clay or leftover earthenware ("crockery"), rolled into balls, then glazed and fired at low heat, creating an opaque imperfect sphere that is frequently sold as the poor boy's "old timey" marble. Glass marbles can be fashioned through the production of glass rods which are stacked together to form the desired pattern, cutting the rod into marble-sized pieces using marble scissors, and rounding the still-malleable glass.