Germany came up with a good design during the First and Second World Wars for their gas mask canister, and it looks like they kept it going up into the Cold War. The West German gas mask can is sturdy and watertight, so it will keep your gas mask, or other goodies, dry. 

Only one is available, as it is from my personal collection. There is some surface rust to it but does not prevent you from using it to its full potential. On the shoulder strap remains the soldier's nametag.