Got my storage idea figured out.

A cheap galvanised toolbox with a lid that doesn't seal (to vent gas/smoke).

My wife plays tennis & 4 tennis balls come packed in a sealed steel can with a tear off lid.

I'll rivet these to the bottom of the toolbox & slip each lipo into individual cans, that way if one
detonates hopefully it won't spread to the others.

Mind you, I've never had a lipo catch fire yet but it can't hurt to play it safe. - John.