Replacing a HDD with SSD is a very popular hack for speeding up old laptop. However most of 2.5 inch SSDs are 7mm at its height while HDDs are 9mm. You must fill the gap with an adapter so that your SDD will not loosen or break its connector when you throw your laptop on a sofa/bed/floor.
Yes you can buy a such adapter at Amazon or other retail store. But if you have a 3D printer at home (or nearby) why don't you create it with your favorite color? And it cost only less than 0.25 USD!
Note: please use double-coated tape 0.25mm thick or less for sticking. Otherwise it exceeds 9mm!