Being an avid photographer, I have always found it difficult keeping the batteries for my shoe mount flash organized. I have bought many different cases over the years that all claimed to solve the issue of keeping dead batteries seperate from charged batteries. Infortunately these cases usually broke after a few momnths of use, or they didn't really do a good enough job for me. Being the resourceful maker I am, I decided to hit up Thingiverse and see if anyone had created a battery case that would hold 4 AA Rechargeable batteries. I was in luck and found this Customizable Battery Case. I modified it using the Makerbot Customizer and placed a recessed lable on the top and bottom that says "Charged" and "Dead" respectively. Print time is about 120 minutes for 2 sets. 

I printed several of the cases on my Lulzbot AO-100 3D printer, (reviewed here) and used the default settings of .40mm layer height with a .50mm nozzle. Plastic was Red ABS from Lulzbot, and was printed at 230c with the heated bed set to 110c. The bed is covered in boroxilicate glass that is inturn covered in PET tape with an ABS Glue layer applied with a paper towel.  These holders fit the super long life, super low discharge Sanyo Enloop 2000mAh AA Batteries perfectly.