In this paper we present progress of an ongoingcollaboration between researchers at the MIT MediaLaboratory and the Royal Academy of Music (RAM). The aimof this project is to further explore the expressive musicalpotential of the Hyperbow, a custom music controller firstdesigned for use in violin performance. Through the creationof new repertoire, we hope to stimulate the evolution of thisinterface, advancing its usability and refining itscapabilities. In preparation for this work, the Hyperbowsystem has been adapted for cello (acoustic and electric)performance. The structure of our collaboration is described,and two of the pieces currently in progress are presented.Feedback from the performers is also discussed, as well asfuture plans.