Kongming Lock Architectural Design

Version with locking components: Easy to assemble, and the addition of locking pieces ensures model stability while keeping assembly straightforward.

Assembly Error Alerts:

This model is a simplified Luban lock that streamlines the configuration of the second-longest shafts, making it easier to print. However, it still presents a certain level of challenge—incorrect assembly (typically due to parts being inserted backward) can lead to more than one loose connection, resulting in an unstable structure (which just means you got it wrong… hahaha!)

This model is a simplified Luban lock, which simplifies the configuration of the second-longest shaft body, making it easier to form. However, it also has some difficulty, as it may be assembled incorrectly and result in more than one hole becoming loose (indicating that you spelled it incorrectly haha).

（）Note: For normal printing, I’ve included an extra small component as a spare!)

The design was optimized based on standard filament properties; since each type of filament expands differently, some joints may feel slightly loose while others are snug. When assembled correctly, the model will remain stable as long as you avoid vigorous shaking or tossing.

When designing, we accounted for typical filament behavior—each material expands at a different rate, so some connections may feel loose while others are tight. The correct assembly method ensures that, with careful handling, the model won’t come apart unless you shake it vigorously.

The Luban Lock, also known in folk tradition as the Kongming Lock or Bagua Lock, is said to have originated during the Spring and Autumn Period. According to legend, Lu Ban, a skilled craftsman from the State of Lu, created a puzzle toy made from six wooden strips—designed to be both assembled and disassembled—as a test to see whether his son was truly intelligent. After his son spent a whole night puzzling over it, he finally managed to take it apart. This ingenious toy later came to be called the Luban Lock. While this story is widely told, the Luban Lock is also known by other names such as the Kongming Lock, Bie Men Gun, Liu Zi Lian Fang, Mo Nai He, and Nan Ren Mu. Its origins lie in the ancient Chinese architectural technique of mortise-and-tenon joinery—a structural system that dates back to China’s earliest building traditions.