This paper describes the development of a modular timber evaporative cooling unit (ECU) possessing a complex dendritic formal quality, presented as a case study, and uses the findings to propose a conceptual prototyping model for the built environment. The case study project leverages computational design methods for design detailing and material optimisation, and digital fabrication for part production. The resultant structure was successfully constructed, however challenges relating to material properties were required to be overcome, these challenges could have been mitigated through a structured approach to prototyping. Reflecting on this project, the paper proposes a conceptual model for built environment prototyping, that combines the insights from established theories to enhance project outcomes.