How can I safely transport fragile items in a cardboard box for international travel?

To safely transport fragile items in a cardboard box for international travel, you should first wrap each item in bubble wrap or packing paper to provide cushioning. Place the items in the box with plenty of padding around them, such as packing peanuts or crumpled paper. Make sure the box is sturdy and properly sealed with strong packing tape. Label the box as fragile and consider purchasing insurance for added protection during transit.