Computers offer a wealth of promises for real-time musical control. One of them is to enable musicians to change the structure of their instruments in the same time they are playing them, allowing them to adapt their tools to their wills and needs. Few interaction styles provide enough freedom to achieve this. Improvised interfaces are tangible interfaces made out of found objects and tailored by their users. We propose to take advantage of these improvised interfaces to turn the surrounding physical environment into a dynamic musical instrument with tremendous possibilities. Methods dealing with design issues are presented and an implementation of this novel approach is described.