Created a simple insert to put in the Rugged Box that can hold 50 AAA batteries.
I printed mine at .2mm layer height on a Bambu X1C in Sunlu Grey PETG.
Requires x6 3x30mm screws.
May require some minor cutting of the lip on the underside edge of the top lid where the gasket is supposed to go if you want a perfectly snug fit.
I've included an extra .3mf and .stl file that include the Rugged Box with this part already cut out for you as well.
The author remixed this model.