I LOVE the design that @Justblair came up with here, and am using it for all of my batteries so I can make sure I cycle through them evenly. The AA and AAA were super easy to print, and work very well. For my Canon LP-E6N batteries, the design needed to be tweaked beyond the parameters in the script, though. The front 'guides' or 'guide covers' needed to be removed a bit from the bottom to allow the batteries to slide all the way down and also be removed.
With that slight mod, this works awesome for the LP-E6N as the curvature at the bottom of the dispenser perfectly suits the battery. This holder retains the batteries securely, you can pretty much drop new batteries from the top on down and they won't come spilling out (well, the first one has to be placed a bit more carefully, but...).
Let me know if you find this useful!
Your choice, I went with 20%