In this paper, we have described the iterative design, implementation and evaluation of a prototype for a collaborative mobile application that is used for sharing photos between two mobile devices. We have introduced a novel way to utilize stereoscopic 3D in mobile interaction by defining a collaborative interaction space, where the private and shared layers are distinguished by the depth where the content items appear, and shown positive responses from the user evaluation of the prototype. We found it remarkable that in the evaluation of the final prototype, participants described the application with terms that are utilitarian – the application was perceived as easy to use, simple, time-saving and fast. This can be seen as a clear improvement when compared to records reported in earlier research utilizing PRC method [7], where off-the-shelf S3D mobile UIs were regarded as visually appealing but containing little to none utilitarian value.