The knife is the basic tool of The Camping Mod. One of it's basic uses is crafting mod related items.
The knife has a couple of uses.
The most basic use of the knife is that, as said above, it is an item needed in some mod related crafting recipes. Anytime a recipe is crafted one durability of the knife will be deducted.
Secondly with the knife any rotatable block in the world can be rotated by a simple shift right-click. Again this will cost one durability.
And lastly the knife can be used as a tool in the Camping Inventory. When the knife is placed in it's dedicated slot, an on-the-go-crafting grid will open, allowing you to craft items anyware! The knife is also still useable to craft items, so no second knife is needed.
To craft a Knife, 3 iron ingots and 3 rose red are needed.