The Microsoft Kinect is a popular and versatile input devicefor musical interfaces. However, using the Kinect for suchinterfaces requires not only signi_x000C_cant programming experience,but also the use of complex geometry or machinelearning techniques to translate joint positions into higherlevel gestures. We created the Kinect Instrument Builder(KIB) to address these di_x000E_culties by structuring gesturalinterfaces as combinations of gestural widgets. KIB allowsthe user to design an instrument by con_x000C_guring gesturalprimitives, each with a set of simple but attractive visualfeedback elements. After designing an instrument on KIB'sweb interface, users can play the instrument on KIB's performanceinterface, which displays visualizations and transmitsOSC messages to other applications for sound synthesisor further remapping.