Many students fail to see themselves as potential scientists or engineers based on established stereotypes of who "belongs" in STEM. Thust, identity and the extent to which it is considered compatible with STEM engagement is a fundamental issue of access. Studies suggest that the Maker Movement is a promising venue through which to build pro-STEM identities across diverse groups. Through the inclusion of materials that are not typical of traditional STEM activities (e.g., electronic textiles, recycled materials), Making creates opportunities to integrate individual and cultural identities into STEM work. However, successfully integrating and scaling up Making into formal school settings requires robust quantitative evidence that is typically valued in policy circles. This paper reports on the development and initial validation of a new approach to quantify shifts in multifaceted identity that are locally meaningful to participants in Making contexts.