A Geller dental arch model includes openings to receive dies. An improvement to the Geller model uses slotted dies, along with complementary support members within the openings of the arch model, to provide proper x, y, and z orientation for the die within the dental model. By avoiding large planar surfaces within the die, this approach can achieve improved fabrication accuracy and better fit for dies and/or arches fabricated with computerized fabrication systems, particularly on surfaces where critical z-axis alignment of a die occurs.