Nikon EN-EL14 spare Battery tray for classroom

A tray to hold batteries for the Nikon D5X00 series DSLR camera (type EN-EL14).
I have a classroom set of batteries and needed a system to organize batteries into charged and depleted. Charged batteries can be placed upright, depleted can be placed on their side.

These batteries tend to fall like dominoes if they aren't secured somehow. Hoping this will keep them from hitting the floor.