Assuming you're talking about flying...
TSA knows what a mod is - I've had NO trouble and I carry a fair amount of stuff. Stuff that LOOKS like detonators, lol.
You want all your vape gear in CARRYON. Batteries in luggage is a no-no, but are OK in carryon. Not sure what VV heard (above), but IIRC, the rules is specific - no batteries in checked luggage. Though you DO want to ensure they are in a container that prevents a short - no loose batteries, please. Liquid is OK, too - just no 100 ml bottles...
edit - I don't pull it out or anything - it's all in my laptop bag. I DO pull the laptop out.
