  The advent of cyber-physical systems, such as robots and autonomous vehicles
(AVs), brings new opportunities and challenges for the domain of interaction
design. Though there is consensus about the value of human-centred development,
there is a lack of documented tailored methods and tools for involving multiple
stakeholders in design exploration processes. In this paper we present a novel
approach using a tangible multi-display toolkit. Orchestrating
computer-generated imagery across multiple displays, the toolkit enables
multiple viewing angles and perspectives to be captured simultaneously (e.g.
top-view, first-person pedestrian view). Participants are able to directly
interact with the simulated environment through tangible objects. At the same
time, the objects physically simulate the interface's behaviour (e.g. through
an integrated LED display). We evaluated the toolkit in design sessions with
experts to collect feedback and input on the design of an AV-pedestrian
interface. The paper reports on how the combination of tangible objects and
multiple displays supports collaborative design explorations.
