9 x CR123A Battery Organizer.
9 x AA Battery Organizer.
They are compact and easily stackable.
I'm working to add more types of battery organizers that are always stackable and compatible with each other so the list of files will be updated gradually.
0.2 layer
2 wall
15% infill
I recommend using a slow speed on the first layer to avoid using brim which would interfere with stacking.
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