If you put a mattress with fitted sheets on top of it, you can see it is not a standard box springs but something metallic. I guess you could put a partial cover around the outside. I invented a new kind of gun safe a long time ago. I took the guts out of one of our toilet tanks and made it into storage for a bunch of my pistols. It was ok until a guest, without my knowledge, went in to use the toilet. When they tried to flush it, they almost shot their butt off.
LoL