This paper describes the development of an Apple iPhone based mobile computer system for vibraphone and its use in a series of the author's performance projects in 2011 and 2012. This artistic research was motivated by a desire to develop an alternative to laptop computers for the author's existing percussion and computer performance practice. The aims were to develop a light, compact and flexible system using mobile devices that would allow computer music to infiltrate solo and ensemble performance situations where it is difficult to use a laptop computer. The project began with a system that brought computer elements to Nordlig Vinter, a suite of percussion duos, using an iPhone, RjDj, Pure Data and a home-made pickup system. This process was documented with video recordings and analysed using ethnographic methods. The mobile computer music setup proved to be elegant and convenient in performance situations with very little time and space to set up, as well as in performance classes and workshops. The simple mobile system encouraged experimentation and the platforms used enabled sharing with a wider audience.