PlayAllAround is a wearable camera-pico-projector system where the scalable interface allows mobile interaction. We access the digital information from the projected scalable interface, which provides both the nearer small-size interface and the farther large-size interface supporting private and public use. The system is in charge of realizing our concepts of an environment independent interface (EII), which focuses on enabling people to access their personal data as well as public resources at any time and any place. In this paper, we propose the design of a reference-cell in the field of ergonomics as well as the principle from decomposition of the application tasks to allow a scalable interface design, with the aim of providing enhanced user experience. We also present the design and the implementation aspects of our PlayAllAround system. We finally describe the evaluation methods and results of the hover gesture and the scalable interface from both the qualitative and quantitative points of view.