A system (100) and method (1805-1855) for modeling binaural shells for hearing aids, wherein the system is configured to load data associated with a first and a second ear shell (1805, 1810). The system is further configured to register the data associated with the first and the second ear shells (1815) and process the first ear shell (1820, 1840). The system is also configured to store data associated with processing the first ear shell (1825, 1845) and then map the data associated with processing the first ear shell to the second ear shell (1830, 1850). Subsequently, the mapped second ear shell is interactively adjusted by an operator to compensate for an inconsistency in the mapped second ear shell (1835, 1855).