Basics
The Crafting Interface is used to tell the network where and how things can be crafted.
By pointing a Crafting Interface to a machine (like a Crafting table or Furnace), this interface will be bound to this machine to handle recipes.
When opening the GUI of a Crafting Interface, you can insert Variable Cards that hold Recipes. This will tell the interface that the given recipe can be crafted using the bound machine.
When you've progressed later in the game, you will be able to craft the Attuned Crafting Interface. It does not require you to manually add recipes to it, as it will read and expose all recipes that are available in the target machine. These are the same recipes that are listed in the Machine Reader Some modded machines may not be supported, which will be shown with a red border when placing the Attuned Crafting Interface.