This article reports on the analysis of a design session, employing conversation analysis. In the design session three experts and a designer discuss a prototype of a shirt, which has been developed with the input from these experts. The analysis focuses on the type of involvement of the participants with the prototype and how they explicate the points they make in the discussion with or without making use of the prototype. Three techniques for explicating design issues that exploit the prototype are identified: a. gazing simultaneously with pointing, touching and/or manipulating (moving, stretching, turning) b. demonstrating by taking the prototype into use the way it is supposed to be used c. demonstrating by imitating the manipulation or use of the prototype through gesture - an ‘imagined’ dealing with the prototype. Based on the analysis, it is argued that these techniques offer different possibilities for discussing design issues.