Do you have a lot of 18650 Li-Ion batteries?
Are you starting to obtain devices with larger Li-Ion batteries?
Are you making DIY Alkaline adaptations to your power sucking devices?
Some simple adapters available here.
Thin adapters are 0.9mm and thick adapters are 1.8mm thick.
Please note for DIY adaptations: Alkaline batteries are not directly replaceable with -any- Li-Ion batteries with very limited exception. They have different voltages.
Also note: These are sized for protected Li-Ion cells to maintain a light hold. You can scale them to 99-98% if you want a better fit for your unprotected cells. Want shorter versions? MeshMixer (Autodesk) makes quick work of trimming their length.
Thick adapters have a taper for "elephant foot" reduction.
Thin adapters are constant thickness.
I print these on blue-tape just to maintain a significant hold to the build plate.
This eliminates sidewalk requirements and artifacts.
However, you know your printer quality better than I.