Well, as long as the juice is non-conductive enough not to drown the electronics I can just submerge them. a charging board, a regulator, and a 900mAh flat LiPo battery can be condensed into a 1" cube, then sealed in clear epoxy and connected to the inside of a twist-off lid.
The lid will act the base for a rebuildable atomizer, having a hole just big enough for a stainless wick to pass down into the jar. put a mini USB port on top also to provide the charging current. fire it with a simple mechanical swich