I used a small Plano ammo can. I took it to a Battery Store and chose the biggest battery that would it in it, a 12v 15 ah sealed battery. The width is perfect, and I cut some heavy foam to fill the end gaps, about an inch on one end and two inches on the other. I used another chunk of foam on top of the battery to prevent it moving if the can were tipped over.
I used the same two wire connector, about $2 at O'Reilly auto parts, plus a fuse block. No switches, I just unplug it. I also bought a battery tender brand charger. It has a plug in that accepts different attachments. The O'Reillys two wire connector is a perfect fit and I plug it into the wire coming out of the ammo can to charge the battery.
I'll try to get some pics posted soon.