Well, the perfect battery case for me I keep my Mavic and battery/chargers etc all in a camera backpack with a DSLR and GoPro plus their equipment. The original battery boxes are great for storing the batteries however their continued use is starting to show and they're becoming weak/torn plus a bit bulky for the backpack.
I found this camera case on eBay for £3.75!!! each. Come from China so took 18 days from order to arrive but for that price. I was a bit unsure of the dimensions but the battery fits perfectly! The outer shell is quite hard and protects the battery well...