1. A method for determining a form for a headphone part, the method comprising: receiving data representing at least one ear model; using a data processing device, orienting the at least one ear model within a coordinate system using the data, wherein orienting the at least one ear model is based at least in part on alignment with respect to at least one area of an ear; using the data processing device, determining a representative model from a plurality of oriented ear models including the at least one oriented ear model, the representative model representing a volume of space common to at least two of the oriented ear models; and determining at least one of a size and shape of the headphone part based on the representative model.