[Carl n Susan]

Most Auto parts stores will make cables for you if you don't want to make them. I have an O'Reily's nearby that does it. Just tell them what gauge and length you want.

If you want to do it yourself, check out Napa stores for cable ends and welding supply places for flexible wire rather than stock battery cable stuff.

As for battery boxes, they are available from Amazon or look for Dyno boxes. But AGMs don't off-gas and don't require a sealed box as do flooded cell batteries. You can just strap them down and be done with it.