Wiethoff, AlexanderSchneider, HannaKufner, JuliaRohs, MichaelButz, AndreasGreenberg, Saul2013-01-032013-01-032013-01-03http://hdl.handle.net/1880/49331There is a well-established culture of early prototyping when designing digital interactive systems, such as paper prototyping and wireframe methods. The culture of designing physical objects is somewhat different: early explorations of form is still prototyped via 2D sketches or renderings, but - mostly because of the construction effort involved - prototyping of actual physical objects is deferred to later stages. The problem occurs when designing mixed physical-digital systems, such as tangible user interfaces (TUI) on interactive surfaces: the high degree of interactivity means that early prototyping is vital, yet there is no viable process for prototyping both the physical and digital aspects simultaneously on a low-fidelity (low-fi) level. Our solution is Paperbox, a toolkit for exploring design ideas for tangible interaction on interactive surfaces. It supports the early exploration of different form factors and immediately provides digital interactivity for the lowfidelity TUI prototypes built with it. We observed our toolkit in use in various settings: as a brainstorming tool by junior designers; in the development of a consumer electronics product in a large industrial company by senior designers; and in a usability study comparing the effect of different levels of fidelity on the outcome. The lessons learnt will enable others to replicate and extend our approach.engInformation interfaces and presentationdesignTangible User Interface, Design Process, Prototypingtechnical report2013-1034-0110.11575/PRISM/30728