Presented herein are methods and devices for designing dental components, such as physical models of a patient's anatomy, crowns and bridges. An operator of a prosthetic designing system can receive information, such as from a scanner, which provides information on the topology of the patient's dentition. The operator can use this information to design a custom prosthetic to fit the patient. Part of the designing process involves using a finish line defined for a preparation as a segmentation line for a physical die corresponding to the preparation, and using a path of draw line as an insertion axis line for a dental prosthetic.