Abstract: In order to better explore the opportunities for tangible interaction in new areas such as the home or cultural heritage sites, we used multiple rapidly-developed prototypes that take advantage of existing technology. Physical prototypes allow us to give form to ideas and to evaluate the integration of form and function, two core components of tangible interaction. We discuss potentials and pitfalls when using off-the-shelf digital devices (by embedding a device, cracking it open and building on it, or collating board and parts) through six prototypes developed in two studies. Hacking devices to materialize our ideas proved excellent for fast prototyping. Technology imposed constraints and prompted different design solutions than initially intended offering unexpected ways to engage. On the basis of this experience we outline a process and offer guidelines for the fast prototyping of tangible interactions. This paper will be published in the TEI conference proceedings and will be available in the ACM Digital Libary.