Tested and works well with PLA. Holds 100 rounds of 9mm ammo and is stackable. The staggered design of the storage allows you to dump 10, 12, or 15 rounds into your hand at once, common amounts for magazines. All parts fit together without the need of using horizontal expansion in the slicer. If you would like to use the STEP files to slice it yourself, import the Letters and Lid files as one object with multiple parts.

Comment if you would like a different size or would like other types of ammo!  I have set up my fusion 360 model to where it can be modified with different parameters very quickly.