Kay has been building didgeridoos since 1991, and his approach is very experimental. He describes his "Test-A-Doo", an instrument with which a variety of sound characteristics can be tested live. In addition he describes a method for the precise investigation of original instruments and detailed building instructions. A special feature of the instructions is the use of computer-created building templates for the construction of an exact replica of a previously tested "desired sound."

His chapter contains detailed designs with measurements, and shows how the required dimensions are achieved despite internal shape changes.