All travelling cases for batteries i found on amazon were kinda crap. So I designed this one, to hold backups for my most commonly used battery types:

• AA
• AAA
• 9V Block
• CR2032

The case is very robust an a good fit on most brands of batteries. It's rough dimensions when closed are 81mm x 37mm x 58mm, which is pretty compact and fits well between the other stuff in a makers backpack.