In typical mass customization design processes, designers encode design processes into configurators that are subsequently used by end-users to customize products. Using the case study of ceramic tableware, we explore how to extend the role of designers beyond the deployment of such configurators. In this paper we describe the development of a generative design system for the mass customization of ceramic tableware, focusing on the implementation of generic shape grammar rules encoded into parametric models. The design system enables designers to develop customizable tableware collections, later to be customized using configurators. Two prototypes are presented and compared, each encoding the design system through different programming environments: Grasshopper and Unity.