The LEGEND experiment has set aggressive goals for reducing backgrounds in pursuit of discovering neutrinoless double beta decay, based on experience gained from the Majorana Demonstrator and GERDA.  Alpha particles originating on or near germanium detector surfaces can be a significant source of background, and the detector response to such signals is being measured by several test stands.  The CAGE scanning cryostat was constructed at CENPA to scan the surfaces of various germanium detectors with a tightly collimated beam of alpha (or beta) particles to better understand the pulse shape characteristics and improve surface event rejection.  In this talk, I will discuss the challenges of building a cryogenic scanning device with millimeter accuracy, the iterative design process enabled by excellent CENPA engineering support, and the current status and outlook of the CAGE system.