  The WeWatt bike serves as an energy station that enables passers-by to charge
their mobile devices through physical activity. However, despite multiple
people using it simultaneously, the bike is typically used individually. To
address this limitation, we developed the WeWattTree, an installation utilising
human-powered energy to filter environmental air. Through the orchestration of
subtle motion gestures, our goal is to entice passers-by to participate and
encourage them to socially interact, synchronising their pace. In this
work-in-progress, we provide insights into the prototyping process, combining
physical experimentation and computational simulation, and delve into the
underlying concepts of our grammar of motion gestures. We highlight how a
single design effectively merged multiple functionalities, how the role of
material characteristics shaped the interaction design, and discuss the
potential for social performances as captivating public displays.
