Traditional interference detection for visualization has taken a virtual-virtual approach, that is, both the intersector and the intersectee are virtual geometries. But, we have learned that there are advantages in combining both physical models and virtual models in the same space. The physical model has many properties that are difficult to mimic in an all-virtual enviromnent. A realistic interaction is achieved by casting the physical model as a 'twin' to the virtual model. The virtual twin has the ability to interact with other virtual models in software. The two combined into a single system allow for a more effective haptic visualization environment than virtual interaction alone.