Bullseye Glass claims these are the best slumping molds they have ever found. They are imported from Creative Ceramics in Europe. The molds are slipcast from a specially formulated clay body, they have an exceptionally smooth surface, accept kilnwash uniformly, and do not crack under repeated usage if handled properly. 12 x 12 x 2.5 in (31 x 31 x 6 cm).
Note: The measurements given here are for the outer dimensions of the molds. This is to help you determine whether a given mold will fit in your kiln. Since they are handmade, individual molds will vary in size. Never cut glass to fit until you have measured your mold.