I needed an adapter to fit 2.5" SSDs into 3.5" HDD bays and all I could find were ones that expected me to screw the drives in. I have a 3D printer, why would I do that? Here's the design I settled on when I got tired of iterating.

Print two and snap them onto either side of the small drive with the I/O ports on the end as seen in the example photo. You may want to snip off one or both of the bumps on the rounded tabs, depending on your SSD design.

This design expects you to be installing this in a screwless drive bay, so you might need to reduce the hold diameter if you intend to screw it in somewhere. The STEP file is provided for this. Please link a remix if you make one.