1. A method for fitting a subject, comprising: selecting one or more pre-generated 3D models for an anatomical portion; capturing images of a user anatomical portion and a reference frame using a mobile camera; generating an updated model of the user anatomical portion by selecting a closest pre-generated 3D model to the user anatomical portion and matching points on the closest 3D model to one or more predetermined points on the user anatomical portion; and selecting a best-fit product from a plurality of product variations based on the 3D model.