My 4TB external Seagate hard drive died recently, right after the 3-year mark. Taking it apart, I find that the drive is made up of a based that plugs into a regular hard disk.
The base still works -- since it's almost always the case that the disk is what failed. If you have a spare SATA hard disk, you can still make use of the based. This setup lacks an enclosure that would protect the disk -- but works fine for a light hard drive such as a 500GB SSD drive.
Here's some pictures of the base, as well as the shopping page with more information about the Seagate drive. The model is outdated, but I suspect similar model would also have a reusable base.
