Abstract: A method for selecting parts for N similar assemblies, each assembly comprising M parts, is presented. A number pm of physical characteristics for each part of the at least M×N parts is recorded, and a value that a group of parts would have if assembled into an assembly is computed until N groups of parts are selected, each group consisting of one part from each of the M groups of parts, and wherein no part is a member of more than one of the N groups of parts, and wherein the value for each group meets a criterion. The method is particularly useful in constructing lenses.