This article describes the motivations and reflections that led to thedevelopment of a gestural sensor instrument called the Quarterstaff. In aniterative design and fabrication process, several versions of this interfacewere build, tested and evaluated in performances. A detailed explanation of thedesign choices concerning the shape but also the sensing capabilities of theinstrument illustrates the emphasis on establishing an ‘enactive’instrumental relationship. A musical practice for this type of instrument isshown by discussing the methods used in the exploration of the gesturalpotential of the interface and the strategies deployed for the development ofmappings and compositions. Finally, to gain more information about how thisinstrument compares with similar designs, two dimension-space analyses are madethat show a clear positioning in relation to instruments that precede theQuarterstaff.