Tested and works well with PLA. Holds 100 rounds of 5.56x45 rifle ammo and is stackable. 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.

This updated version has the grid lowered down, so the bullets can be stored point up or down, whichever is preferred.

Please 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.