I'll be honest, I'd be amazed if anyone ever needs this! I have an odd use case of reusing an old mSATA SSD for my home server's boot drive and the hole spacing on it is totally wacky and doesn't fit anything. If you also bought one of those, maybe this will be any use. Probably not!
An example of the adapter in question: https://www.ebay.com/itm/151466719602
These are often mislabeled as pcie or m.2 drives, which is NOT what this is for!
For kicks I also included an openscad file of the reference model I made when measuring the dimensions of it.
The board mounts to the part with standard PC case screws. The hole spacing is equivalent to the lateral hole spacing on the underside of a 3.5" HDD, if that's ever any use.
The author hasn't provided the model origin yet.