The carrier has curves wherever possible so that there is no "joint" where the handle can pull apart.  They can also be stacked Jenga-style when empty.

You can further distribute the downward force by adding zip ties between the holes in the handle and the divider in the base.

BONUS: The opening in the handle fits 2 stacked wide-mouth plastic lids (for drying).

Print in PETG if the carrier will spend long hours outside or in a hot car or barn.

Tolerance is 0.25 for to allow for variation among filament brands.