2008 Apple XServe 2.5" Hot Swap Drive Bay Adapter
My XServe had a 3.5" SAS drive die over the weekend, we have hundreds of spare 2.5" SAS drives so I took the chance to standardize it by making an adapter in Inventor Fusion.
After 6 revisions (revision 5 is pictured with the drive, only difference is minimizing the material usage) this is pretty darn perfect.