A book you are automatically given by the game itself once you craft the Smeltery Controller.
It will tell you the exact quantities of the items needed to complete a working, basic Smeltery. It will also tell you some of the basic functions of what the Smeltery can do (alloys, special blocks, etc.). The instructions to create the Smeltery parts are located in the copy of Materials and You that you get at the beginning of the game when you spawn.
Mighty Smelting can also be made and copied numerous ways on the crafting table.