Most improvisation occurs inside constructed environments, as we have pointed out already. But what relevance does improvisation have to constructed environments themselves? It is pertinent from the point of view of both the architect and the users. Architecture, the production of constructed environments, is a practical as well as artistic activity. So it is worth discussing the procedures in its production, and their relevance. Note also that in Appendix 1 we propose and investigate the possible construction of environments specifically intended for the use of improvisors: this does not seem to have been attempted to date.