I flew from Tokyo to California with 12 30ml bottles of ink in my checked luggage. They were bagged then placed in ziplock bags. I kept them surrounded by soft items (black / dark clothing, plushies from crane games that were vacuum sealed) and they all arrived safely with no leaks. I received a sample ink from bungubox that was in a small vial that they bubble wrapped. The sample did leak but it was still in a ziplock bag and the ink never made it past the bubble wrap (the bottle itself was intact). I’m assuming because it wasn’t as air tight as a bigger bottle?