Papanek indicated how to increase your market; design for one very well and look for others who share the same needs. (Papanek 1974) Increasing your target market may be achieved by finding other User Task Enevironments (UTE’s) that require the same or very similar product design specification, Product Design Specification (PDS).
A powered drinking device, the Autosip, designed for the Motor Neurone Disease Association by the author in 1992 (Burkitt 1995) provides a good example for this principle.
Although initially designed for people living with Motor Neurone Disease (MND), it was found the product was also useful for people with similar physical disabilities, such as Hemiplegia (stroke), Muscular Dystrophy (MS), and Arthritis.
Useful links
Burkitt, J., G. Martin, G.H. Kay, G. E. Torrens, C. Chapman, and D. Sandbach, 1996. The development of the port-a-bidet: A portable bidet for people with minimal hand function. Medical Engineering & Physics 18, (6): 515-8.
Burkitt, J. A., G.E.Torrens, G.H. Kay, D. Sandbach and I.A. Sutherland, 1995. The development of the Autosip: A hygienic, self-operated, drinking device for people with minimal sucking ability and/or minimal arm strength. Journal of Rehabilitation Sciences. 8, (4): 115.
Torrens, G.E., Marshall, R., Burkitt, J. and Kay, G., 1996. Using modularity to produce more competitive assistive technology products, Proceedings of the 13th Irish Manufacturing Committee , Limerick, Ireland, pp 797-804 Available at: (https://dspace.lboro.ac.uk/dspace-jspui/handle/2134/15775) , Accessed:[23/09/2015]