In this paper we present MESMER, a work-in-progress tangible conversation tool for playful design. Our work extends the Otherworld Framework (OF) [7] for tangible tools by centering specifically on play as a conversation topic. Here we unpack how early experiments with OF motivated our work and describe the current iteration of the MESMER tool, which comprises persona cards, various boards, and a shared physical token. MESMER is inspired by our findings from early trials with OF: performative playful interaction promoted playful and divergent thinking; embodied non-verbal communication led to shared insights, the board's contents and structure helped scaffold conversations, a diversity of personas and narratives seemed desirable, and roleplaying personas encouraged multi-stakeholder empathy. Our ongoing research aims to help designers and researchers to facilitate engaging, fruitful and inspiring conversations where diverse stakeholders can contribute to playful technology design.