I decided to go for the metal box route, after looking at tool boxes and other options this metal storage that was on sale at SupercheapAuto fitted the requirements perfectly. And its red for danger ....
This is is the new charger I got.
First step was to cut a 22mm hole in the lid to first allow the charging cable out and also be first of the vent hold if there was a lipo go bad situation.
I also added 4 more 10mm holes for venting.
Next was to drill holes for the power plug to external power supply. The paint was scratched to allow for better hot gluing.
I also hot glued a spring into the hole so since I didn't have a rubber grommet to protect the battery wires.
Next I had to wire up external power to a plag that fitted the charger. Solders done and then heat shrunk.
The the bits sitting inside there new home.
Now charing a battery for storage. The charger sits outside and the batteries on the inside. Pretty happy with the little charging safety box. Now I can charge with more peace of mind that having them just sitting on the work bench.