I fly with my stuff all the time and it's no problem. In the US, we have to carry all our liquids in a quart-sized ziplock bag. No matter how hard I screw down the caps, the bottles *always* leak. It never gets out of the ziplock, though.
All of my toppers, tanks, etc . .anything that can be "juicy" goes into a waterproof Otter Box that I carry in my laptop bag. My ego batteries go into a side pocket. My 18650's, etc, etc go into my carry on bag rolled into socks so they can't touch each other or anything else. Lastly, an ego with a filled evod goes into my laptop side pocket for use in the bathroom during plane-changes or immediately upon leaving the airport. I've never had juice leak from the evod during flight.
I often bring a small box with DIY supplies - cotton balls, nail clippers, wire, multi-meter, etc. Working on builds helps pass the time in the hotel room.
The *only* issue I've ever had is with my Magneto. For some reason I get stopped by security everytime I bring this. They take it out of my bag, ask me what it is, take it apart, send it through x-ray again, etc. They never have noticed any of my other mods. It's kind of a pain but I like my Magneto so I bring it, anyway.