Purchasing RAM and SSD upgrades from laptop manufacturers when ordering is a big rip-off (and the selection is limited), so I almost always do this myself. Unfortunately the latest generation of Lenovo Thinkpads has greatly reduced reparability, now requiring a spudger to remove the entire bottom part of the case to accomplish these tasks. Even with that extra hurdle, I decided to go for it myself.
The process is relatively well documented in the Thinkpad hardware maintenance manual and on youtube, but that doesn't make it easy. Undoing roughly a dozen clips inside the tightly fitted case, even with a spudger, is no easy feat. I did manage, after much time and frustration, to complete the process, but significantly marred the plastic spudger and very slightly marred the case near the front right corner :(. Still, the result is *much* better than if I'd tried doing this with my fingers or a screwdriver (I attempted a much simpler process of separating a T61 bezel a few weeks earlier without proper tools).
The spudgers are helpful, but no magic bullet. Shame on Lenovo for this design change (but Thinkpads are arguably still the least bad laptop on the market).