I was trying to build a Pi NAS box with a Pi4 which I had spare, and an existing USB Seagate 4TB HDD which i regularly use for backup. Was going to design my own enclosure/case to hid all the cables, but found this original design instead. This original design was great, and only needed some modification to work with the external hard disk. Instead of standoffs for regular sata HDD, i removed those, and put in a bracket so that the seagate HDD doesn't slide around too much. I really like this design, hope it works well for you as well. Kudos to the original designer for making such a cool enclosure and saving me a lot of time :)

Note that i included the OG design in the 3MF, I didn't end up using the feet. i also didn't screw my enclosure together. If you need instructions on how to put together the case, please go to the link of the original design, it's great and super clear!