Many companies that struggle with product variety and configuration management issues turn to a module-based design approach. Although this approach is well-known to be efficient for managing variety of a product family, current methods do not enable designers to handle both modularity and variety within a product family. The Design Structure Matrix (DSM) has been widely used to identify modules within a product, but its use to identify modules across a family of products has been limited. In this context we propose two tools based on an extension of the basic DSM to manage variety of an entire product family. The Variety Design Structure Matrix, DSMV, handles variety of the product family and 3D Design Structure Matrix, DSM3D, enables visual analysis of across the entire product family. These two tools, combined into a single approach, enable analysis of the product family at many levels - family product, module, and interfaces - to better specify modules and interfaces across all of the products in the family. A case study involving a family of three single-use cameras is used to demonstrate the application of these new DSMs and accompanying cross-module and cross-interface analyses. This new approach can be applied during detailed studies as well as in the early stages of the design process.