This paper discusses a design strategy for assistive equipment for disabled people, in particular for special switches and control systems to enable the severely physically handicapped to control powered wheelchairs, computers, communication aids and environmental control systems. Special switch systems in this application must provide a complex human-equipment interface. Experience over a number of years with over 80 severely handicapped young people has refined the design strategy for both special switch systems and interfacing. Some examples are given of a problemled approach, and the materials used and the method of manufacture are discussed.