<p>Traditional mechanical engineering education often encounters challenges due to insufficient interactivity and intuitiveness. In recent years, virtual reality (VR) technology has emerged as an innovative solution to enhance engineering education and training and has demonstrated remarkable effectiveness, particularly in mechanical engineering. However, existing virtual assembly training systems still suffer from two primary limitations. First, the absence of a coherent systematic development framework results in inefficient prototype construction. Second, the widespread adoption of single linear paths ignores alternative assembly sequences, thereby restricting the realism of the user experience. To address these issues, this paper proposes CRUD, a physics-based multi-path assembly framework. By innovatively introducing a topology-sorting-based multi-assembly path mechanism and establishing a 3D game engine development framework paradigm accessible to non-computer professionals, the framework significantly enhances the flexibility of assembly path selection while reducing the entry barrier for VR assembly prototype development. Finally, based on the proposed methodology, the framework was instantiated using Unreal Engine, and a virtual assembly prototype system was developed and experimentally validated. The results show that CRUD is an effective framework, providing valuable references for the development of similar virtual disassembly and assembly systems.</p>