3-D digitizers are tools that can be helpful for Reverse Engineering. With a digitizer, you can generate a computer model from a physical object by sampling 3-D coordinates one at a time to create input curves for surfacing commands. Since each surfacing command requires specific input curves, an experienced Rhino modeler must decide the best surface creation tools to use to duplicate an object's shape. With a 3-D digitizer, you can sample the points needed to create the required input curves. 3-D digitizers can also be used for inspection. By sampling points in critical areas on the physical model and comparing those points to a digital model, you can judge the accuracy of the digital model.
Learn how to connect your digitizing arm to Rhino, calibrate probes, and orient Rhino with the real world:
These documents have been around a while but apply to any digitizing arm and version of Rhino.