Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5156560.

Parametric minimalistic ammo tray, for all you reloaders out there. Diameter of the case inserts, height of the walls, and sturdiness can all be controlled by changing the parameters in the f3d file, and the included STL file is already sized to hold 50 223/556 casings, and any rifle caliber of a similar dimension. Trays are also interlocking and stackable, for easy storage

Print with the open side of the inserts facing down, directly on the bed. So long as your printer can handle minor bridging these print just fine without supports