In this paper, we present a novel device concept that features double-sided displays which can be folded using predefined hinges. The device concept enables users to dynamically alter both size and shape of the display and also to access the backside using fold gestures. We explore the design of such devices by investigating different types and forms of folding. Furthermore, we propose a set of interaction principles and techniques. Following a usercentered design process, we evaluate our device concept in two sessions with low-fidelity and high-fidelity prototypes. Author Keywords Tangible interaction, mobile devices, dual-sided display, foldable display, flexible display, folding, input techniques. ACM Classification Keywords H5.2. User interfaces: Graphical user interfaces (GUI), Input devices and strategies, Interaction styles. General Terms Human Factors, Design, Experimentation.