This paper present results of our investigations into using spatial augmented reality to improve kitchen design and other interior architecture tasks. We have developed user interface techniques for room sized modelling tasks, including cabinet layout, viewing and modifying preset designs, and modifying materials and surface finishes. These techniques are based on Physical-Virtual Tools, which consist of physical input devices augmented with projected information. These tools and techniques address key user interface issues for spatial augmented reality systems, and we discuss how they can be generalised for other applications. The techniques have been developed in the context of a demonstration application, BuildMyKitchen. BuildMyKitchen allows architects to design kitchen cabinets and layouts, and work with clients on the design, in an interactive spatial augmented reality environment.