We present MochaTop-a system using multiple mobile devices that is part of our on-going inquiry into ad-hoc multi-device environments on tabletops. In this progress report, we describe the motivation for designing multi-device, ad-hoc systems for single and multiple users, and explain the design and implementation of our prototype system. We report on preliminary user studies made with focus groups and sandbox explorations of the prototype, with video analysis. By designing new interaction patterns, we focus on investigating if multiple mobile devices can be used to transform everyday settings into new environments for data exploration. Our research indicates that users value the extended interactive space created by multiple mobile devices.