A computer system was created to help beginners in mechanical engineering learn about building 3D mechanisms. The system uses simplified blocks to simulate how different parts of a mechanism move. In this study, a 4-bar linkage mechanism was implemented to show how motion can be converted. The system automatically determines the positions of each link based on the driver link, making it easier for users. The user interface is designed for learning, with the driver and fixed links specified in advance. A model of a treadle machine was created to demonstrate the system's usefulness.