This paper describes the interactive strategies adopted during the composition and realisation of construction 3 for soprano saxophone and multiple media, by Tony Myatt and Peter Fluck. This work is an interactive multiple media composition for computer, computer-enhanced saxophone and computer graphics projected onto irregularly shaped screens. Derivation of the performer sensing system and mapping strategies to control signal processing, computer generated materials and communication gestures between the performer and computer are described. These processes include generative mapping techniques using neural networks for the recognition of gestural information and the development and application of wireless, wearable sensing technology. This work is described as a holistic approach to the derivation of performer sensing, data mapping and the application of reactive and interactive processes in the context of the creation of a new musical and multiple media composition.