Kongming lock is a traditional Chinese intellectual toy. It is said that the toy was invented by Zhuge Kongming some 2,000 years ago based on the principles of the eight-diagram metaphysics. It was widely popular among the folks. The concave and convex parts inside the three-dimensional interpolation toy mesh perfectly. Kongming locks come in different shapes and sizes, with different internal structures. But they are usually easy to take apart and difficult to reassemble.