In this project we explore the use of mixed-fidelity (paper and digital) prototype design as a method for prototyping and testing mobile applications in realistic situations of use. The project is based on the work of a former DTR undergraduate researcher, Kevin Chen, who built a system that allows designers to stream a paper prototypes from a desk to a user's mobile device. We build off of the RPPT platform by introducing digital elements -- native smartphones elements such as a digital keyboard or camera viewfinder -- to a low-fidelity environment. To incorporate these digital elements into the platform, we developed a technology that uses Prof. Michael Horn's topcode system to translate between the paper and digital prototype, triggering the appropriate digital elements to be overlaid at the appropriate location on the user's device. We hope our system reduces the amount of work required on part of the designer in both building and testing the prototype, allows the user to focus on the design at hand by providing them with a realistic use experience (through testing in-context and interacting with native smartphone elements), and provides an outlet for designers to prototype app experiences that couldn't be prototyped using previous techniques.