How do I make a Crafting mechanic? [closed]

This is not a constructive question in its current form. It looks to me that you don't know how you want the crafting system to function at all, so it's impossible to make what you ask.

Additionally, Scripting Helpers is not a request site. You're much more likely to get help if you attempt to make this own your own. Asking more specific questions about various methods you're attempting is okay, but asking for a crafting system as a whole is not.

To start with, I suggest you figure out how you want the crafting system to work. Here are a few questions you'll have to answer:

1) How are items "placed" on the ground to be crafted?
2) How do you "craft" the placed items?
3) Where does the crafted item go once created?
4) What will happen for invalid recipes?

This is design work, and does not involve any programming. Once you figure out at least those answers, and any more relevant information to how you want the crafting system to function, edit your question and I will give you some pointers as to what code methods you should look into.