The answers to this question greatly depend on your targeted destinations. And if it’s a foreign country, then the chance of you being able to carry your multitool on the plane, especially the pocket knife, is often minimal. And the reason for this is to minimize the potential threat for the customers as well as the crews, should something unusual can arise. Hence, you won’t be permitted to bring your multitools on the plane, as long as they come with a mounted blade or something similar. However, if you’re traveling domestically, there is no law that prohibits you from bringing your multitool, especially when you’re travel alone. Just make sure that you don’t bring your pocket blades on trains, ferries, or any other public transportations.