A customizable battery case to hold batteries while traveling. Configurable for the number of batteries and type (as long as they're cylindrical). This is a updated version of the customizable battery carrier ( https://www.myminifactory.com/object/customizable-battery-case-magnetic-18159 ), re-designed to work without magnets as requested by GregFisk25.
Create a top and bottom piece (the sum of the heights of the two parts should be equal or slightly larger than the battery height, you can divide it up any way you want).
for reference, here are some common battery heights:
AA - 50.5mm
AAA - 44.5mm
CR123A - 34.5mm
CR2 - 27mm