How to Make a Crafting System?

I am making a game where you can combine various objects to make weapons, barricades, and items, however, I have absolutely no idea how to go about making a crafting system. Is there a script that someone could provide, or does anyone have any ideas? For example: if the player has three chairs in his inventory, he could craft the three chairs into a barricade.

http://forum.unity3d.com/threads/90871-advanced-inventory-system-example here try this i made it enjoy :slight_smile:

Thank You so much!