Easy, I made a bunch of little "Books" that I was going to put in my game. (Each book had 3 things you could make, but things can get very long if you need a bunch of materials, so I'm probably going to switch over to scripts)
Okay, lets say you want an item to allow you to make items. (Like a book or whatever in your inventory)
You will need to make a common event first.
Make text saying something like, "Do you want to make a Bananarang? It requires 1 banana and 1 piece of pure awesomeness."
Then have a choice event saying yes or no.
Under the "YES" or whatever you named it, set a conditional branch (Under comment on page 1) seeing if a Banana is in your item inventory.
Make another conditional branch just under the one you just made looking for a piece of pure awesomeness.
Now, just under the second conditional branch, put text saying something like "Made bananarang" Now take away the banana and the piece of pure awesomeness and add the bananarang.
There is a section in the conditional branch saying "else" DON'T put the eventing there, put text in the 2 "else" saying "You do not have the ingredients to make this." or something similar.
Then link the item (book or whatever) with the common event.
And there you have it. Hope this helps.