Occasionally your slumped glass rocks because the bottom of your mold isn?t flat. Take care of that problem using this bottomless mold.Constructed of earthenware ceramic after creating this gentle curved piece with mitred corners, this kiln forming mold allows you to make a square bowl with a flat bottom.This mold will host a piece of glass that is up to 8 inches long x 8 inches wide (of any thickness you can create). The depth of this mold is 1.75 inches.