Craighill's beautiful mechanical puzzle comprised of three identical pieces, die-cast in stainless steel and weighing half a kilogram. The Venn Puzzle is a surprisingly difficult dexterity challenge and an intriguing addition to your desk, shelf, or coffee table. The assembled puzzle creates a perfect sphere — so each piece makes up one-third of the sphere by volume. These pieces are cast from molten stainless steel in a ‘die’ or mold at temperatures over 2500°F.