The BackTools Mod adds a feature which makes it possible to carry tools on your back. You can carry everything from pickaxes to swords. Not only does it look totally badass but it is also quite useful as it frees up one slot in your inventory.
To carry a tool on your back simply hold the item in your hand and then tap on the ground to place it on your back. To hold the tool in your hand again press the B button on the right side of the screen.
Here is a list of tools which you can carry (more will likely be added in the future):
This is an early beta of the mod so it’s not perfect. But it’s definitely useful as it will free up one slot in your inventory when you carry a tool on your back.