i fly alot. this was my first time with vape gear though..i just flew usa to mexico. i put everything in my checked luggage.. it made it through fine. nothing leaked either.
in the U.S>
if you are going to carry any kind of liquid on your carry on, it has to be in clear plastic bag with all your other carry on liquids. They always make you take your liquids bag out of your carry on for security scans. if there is anything.. even a little liquid bottle still in your bag they will stop you and ask you what it is. It probably wouldnt be an issue if they did, but just something to know
also, if you are flying with anything larger than an ego, especially with something like a rebuildable, or something with a large carto tank on it, i would suspect they would be more suspicious.
the issue is that if you put it in your checked luggage, they may simply find it, not know what it is and confiscate it, or worse someone could steal it (has happened to me before with other "expensive" items.
but if you put it in your carry on, it may also look suspicious and get confiscated...
it always helps to put things like that in your luggage in a way that looks organized, clear, clean, and even labeled. security people look for bags that are jumbled and disorganized.
dont vape in a plane.. just dont. if you need a nic fix that bad get some gum.