The file '3.5″ Generic HDD Caddy 3D Printer Model' is (stl) file type, size is 126.1KB.
A generic hdd caddy for a 3.5" hard drive. The caddy uses 4 standartized pc case screws like https://www.aquatuning.co.uk/media/image/af/5b/d6/94577_1_600x600.jpg
You can find a generic 5bay cage here: https://www.thingiverse.com/thing:4106284
and a customized 4 bay cage for the Thermaltake V21 here: https://www.thingiverse.com/thing:4106305
Update
A second version with more airflow added
hdd_caddy.stl | 332.8KB | |
hdd_caddy_airflow.stl | 348.2KB |