Raw aluminum is a very reactive material and corrodes quite fast, I'm not sure if I'd like to chance vaping with it raw. You should either anodize it or clear cote it. I had a bunch of stuff hard anodized for my subaru and was surprised at how reasonable the prices were.
Aluminum oxidized within a few seconds. It forms a layer of oxide which protects the metal well. BUT: never use an aluminum-lead alloy. Use only AlMgSi0.5 or AlMgSi1. In germany also called "Seawater-Aluminium".
All my mods are only made with ALMgSi0.5.