A method and appertaining system implement the use of manufacturing protocols for hearing aid design such that the ability to build an instrument can be displayed as a numeric parameter based on the partial numerical and metrological contributions of all the essential parameters of the given impression, and a buildability index can be displayed as a 3D virtual image of the proposed shell or preferred shell types. The method utilizes a predefined parameter table comprising parameters to utilize for a buildability determination. The buildability index is computed based on impression shape data, selected shell type, selected number of device options, data obtained from the parameter table, and data obtained from a receiver table, and the buildability index is output to a display of a user interface device or an external system.