Form versus function is a classic design debate. In this article, a practical approach to combine shape pref- erence (form) and engineering performance (function) under a design optimisation paradigm is proposed and implemented. This synthesis allows form and function to be considered in quantitative terms during the design process to identify shapes that can benefit overall product design. Two methods of preference modelling, PREFMAP analysis and conjoint analysis, are used to model user preference as a mathematical function of design variables. Physics-based models express engineering performance as functions of the same design variables. The models are combined in an optimisation formulation to capture the design trade-offs involved. A simple illustrative study of bottle design is presented. A divergence is found between the most preferred shape and the technically optimal shape; a Pareto frontier provides insight into the trade-off between these two goals.