1. A method comprising: receiving medical imaging data representing facial anatomy of a patient while the patient is wearing a scan prosthesis against the patient's soft tissue; receiving medical imaging data representing the scan prosthesis; processing the medical imaging data representing the facial anatomy of the patient and the medical imaging data representing the scan prosthesis to generate a three-dimensional model of the facial anatomy and a three-dimensional model of the scan prosthesis; creating a modified hard tissue model of the facial anatomy by adding one or more support structures to the three-dimensional model of the facial anatomy; and molding a model of the patient's soft tissue between the three-dimensional model of the scan prosthesis and the modified hard tissue model by pressing the three-dimensional model of the scan prosthesis against the one or more support structures.