An advantage of physical interfaces over graphical widgets is that they bring controls closer to hand. VoodooSketch is a system that supports dynamic customisation of tabletop interfaces with physical controls that users can arrange on palettes. The system employs pen and paper techniques to achieve two novel capabilities: first, users are able to sketch controls that are immediately operational for pen interaction; second, users can label the controls with a handwritten name that identifies their function and binds the control to an application. This paper presents the results of an empirical evaluation of the VoodooSketch interface custom isation techniques. The main findings of the study are: that users are able to easily create sketched controls; that they can use them as effectively as traditional input devices; that handwritten labelling is more efficient for control mapping than conventional screen-based methods; and that the sketched controls improve user performance and reduce error rates.