This document discusses designing circular business model experimentation through case studies. It aims to increase understanding of how to design circular business model experimentation while considering both company and research organization needs. Elements involved in designing circular business model experimentation are explored. Differences between company and research organization data collection objectives are examined. Rapid business model experimentation is proposed using rapid experimentation cards covering working hypotheses, data collection/analysis, and criteria for validation/rejection. The document concludes that rapid experimentation, partnerships, practical implementation, iteration, mindset change, and learning from multiple data sources can aid the design of circular business model experimentation.