Indoor mapping data is crucial for navigation and accessibility, yet such data are widely lacking due to the high manual labor of data collection, especially for larger indoor spaces. We introduce Drone-based Indoor Accessibility Mapping (DIAM), a drone-based indoor scanning system that efficiently produces 3D reconstructions of indoor spaces with key accessibility facilities recognized and located in the model. With DIAM, users can scan indoor spaces quickly and generate a precise, detailed, and visual 3D indoor accessibility map. We describe DIAM’s system design, present its technical capabilities, and discuss future use cases.