Mapping construction material stocks is essential for understanding socioeconomic metabolism and informing the circular economy. However, existing spatial material stock (studies often produce coarse results due to challenges in material inventory (MI) development. This paper proposes a structured, systematic approach to enhance MI data collection. We introduce a new template for collecting MI data in buildings, designed with three core objectives: (1) to streamline the data collection process during building sampling, (2) to support cumulative research while ensuring project-specific relevance, and (3) to enhance the utility of results for the construction industry. BUD-MI, the proposed template, aims to assist researchers in MS modeling, students, and construction practitioners in understanding building material profiles. Using design theory, the development process includes identifying MI challenges, requirement elicitation, domain component mapping, and component assembly. BUD-MI consists of four data input tabs, two mini-tools for data input assistance, four result generation tabs, and additional tabs for background data and ancillary information. A case study in Sheffield, UK, illustrates BUD-MI's functionality, enabling bespoke MI results to be disaggregated across building elements and components. BUD-MI supports future MI data collection efforts, ensuring data quality, granularity, comparability, transferability, and availability, thereby advancing socioeconomic metabolism and circular economy research and practices.