What about an old west themed box? I think it could work really well. There's plenty of stuff in game already for reskins, for example:

Swords: maybe a troika reskin that looks like a pickaxe, to show the gold rush and mining

Guns: the 5* Antigua guns would be perfect, as they are basically revolvers.

Bombs: could be a splinter bomb made of tnt or something. Or another BAB reskin, but there's already a few of those.

Costume armors could range feom dusters to sheriff coats, as well as bandit clothing.

Accessories could be badges, hats, handkerchiefs, spurs, etc.

Overall I think this could be really cool, and would be up there with the pirate and Viking promos. Let me know what you guys think!