To follow up on what's already been said, to get your LTW primary tool you MUST go register at the guild in Gridania. They give you the level 1 primary tool and it is the only way to get it.
For leatherworker your primary tool should be a head knife. If you have an awl, that is the secondary tool which can only be equipped once the primary tool is already equipped.

To expand on Shmunkster, once you have created an outfit set you can also drag it to a hotbar slot. I have a permanent bar that has all my crafting classes on it for easy switching.