Jim,
I use a Sear Craftsman tool bag for the tools. I use the ammo case for the batteries. I took a piece of aluminum flashing and bent it to form vertical separators that I slide the batteries into. I mark the battery ends one side with green tape the other with red. I put them in green side up when they are charged and red side after a flight. Has worked well for several years, you can get the ammo case at an Army/Navy store or online, under $10.
Best, DennisT