prototyping products during collaborative design

Liz Sanders has done some interesting work with prototyping tools to use with users. She has a cool velcro set that allows crafting different form factors and modifying them without a degree in ergonomics.

Sanders, L. (2003). Collective Creativity. LOOP: AIGA Journal of Interaction Design Education(7).
pdf or html (which has a few larger versions of the images available)

This type of low-fidelity prototyping is a necessity for rapid creation and re-creation of product ideas without the overhead of coding or limitations of more "advanced" prototyping tools.