This paper presents an analytical approach that we call the focus framework. The framework aids the analysis of the intended and unintended design attributes that emerge within a project's design process. The framework helps to reveal how prototypes and decision making interact together to shape the final design features and make visible the trajectory of central design attributes and unexplored alternatives. In this paper, we report on the framework and its development by way of a retrospective analysis of a tangible light installation we designed known as the Urban Data Posts. We see the potential for designers to use the focus framework as a post-mortem tool to retrospectively analyze their own work and thus inform their design practice. The knowledge gained through the analysis can then be applied in future projects more generatively.