This thesis, NonSense Bazaar: Designing for Shared Worlds, questions the dominance of human-centered design and explores how speculative, more-than-human design can transform the way we imagine the future. Design has long operated primarily for human needs, often at the expense of ecosystems, leading to the current ecological crises. This research suggests a paradigm shift in designing with all living beings, realizing that humans are only part of an interdependent web. Drawing on posthumanist philosophies and indigenous knowledge, the thesis focuses on the NonSense Bazaar workshops. Participants experimented with speculative persona design and diegetic prototyping, creating artifacts like vulture claw extensions and interspecies currencies. These workshops tapped into the transformative potential of design when channeled towards empathy and planetary care. Supported by a handbook and website, this thesis encourages a redesign of design as a collective care practice, moving from extraction to relationality and coexistence in an age of crisis.