Hearing aid battery holder / keyring

Hi, 

What do people use to keep spare HA batteries with them at all times? 

I have one of these Rayovac keyrings, which seems to be the only product available specifically for this purpose, but it's a bit cack. The drawer keeps falling out and spilling my batteries everywhere. I bought a little, metal stash keyring thing, but didn't appreciate that coming into contact with metal would render the batteries inoperable. 

I can't be the only one looking for such a product, so what do you guys use?