As CAD tools become more sophisticated, engineers are able to more easily create complex part geometries with minimal mass given strength and stiffness requirements. However, these complex part geometries can be difficult to subtractively manufacture, which consequently increases manufacturing cost and production time. This thesis presents a method independent of CAD kernels for use early in the design process to automatically evaluate a given part's machinability and to provide visual geometric additions that decrease manufacturing cost while maintaining the part's strength and stiffness requirements. Slicing a single part into multiple sub-parts, which are joined together after undergoing pre-machining, offers additional possibilities for cost reduction and machinability improvement by utilizing smaller stock material that requires fewer machining operations. The resulting part geometry for each candidate is determined by intersecting the machinable geometries for each individual machine setup, and may have some amount of added volume over the as-designed part. Evaluating and culling candidates based on two objectives (added volume and cost) provides the design engineer with a set of Pareto-optimal solutions that show where material can be added to reduce manufacturing costs. These methods are implemented and tested on five example parts to demonstrate their capability and utility.