Craighill Venn Puzzle (Stainless Steel)A beautiful mechanical puzzle comprised of three identical pieces, die cast in stainless steel and weighing almost 2 pounds. The Venn Puzzle is a surprisingly difficult dexterity challenge and 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 2500F.