Perfect carrying case for traveling with 18650 and 21700 batteries.
I ran across this case at Lowes the other day. Very sturdy, adjustable dividers and very low profile. Perfect size for under-seat car storage or luggage. $ 7.48 at my local Lowes.
AA Battery Storage Case by Garrett MakerWorld: Download Free
Print two (One for bottom and one for top). You can add magnets if you would like to make it more secure. I used 8mmx3mm neodymium magnets to keep the lid from falling off as I grab the