I created this parametric battery case for use when traveling with lithium batteries. Airlines don't allow you to put these types of batteries in your checked bags anymore and I was tired of just throwing mine in a plastic bag. It's parametric so you can adjust this box to fit any kind of cylindrical battery (AAA, AA, 18350, 21700, etc.) and by adjusting the length and width of the box you can also increase the number of batteries the box holds. The pictures and the print files are for a case with 3, 18650 batteries and require 6, M3 x 30mm screws. The box lid in the attached print files allows for a small amount of foam to be added inside. The battery fit is fairly loose to allow them to come out easily. The foam helps hold them in place. This isn't required but is recommended.