those batteries interest me are they the same size as standard AA's?
if so that might solve an issue I've had with my old redcat sumo I modded a few years back, and couldn't find a lipo to fit strapped to the sides.
As for a fire box I charge my batteries in a army ammo can I got from a army surplus store. On ebay people have tested them purposely setting off lipos in them, and they worked great in putting out the fires without causing any damage to the surroundings. In one test it put out the ruptured cell so fast the cell that it was glued to was still good