Direct download link for the STL: https://git.cryto.net/joepie91/modular-hdd-rack/raw/branch/master/tray.stl
I designed this rack as a way to extend my NAS, as I've run out of drive bays. It's designed to sit *next to* the NAS itself. It can also be used for cold storage of drives; it's pretty space-efficient, and can stack pretty high.
Video here: https://www.youtube.com/watch?v=18qHf6oyXV8
