Anvil is a block added by ExPetrum.
Anvil can be obtained by crafting from 7 metal clumps/stones:
An anvil has an associated material and tier with it.
Different recipes require different tiers of the anvil. Usually it's the tier of the metal used in the recipe.
The following materials have associated tiers:
Stone: -1
Copper: 0
Bronze: 1
Bismuth Bronze: 1
Leaded Bronze: 1
Manganese Bronze: 1
Aluminum Bronze: 1
Iron: 2
Steel: 3
Stainless Steel: 3
HSLA Steel: 4
Tool Steel: 4
Anvil has an interface that can be opened by right-clicking it:
The bottom-right slot is for flux(either Metallurgic Charcoal Flux or Bone Ash).
The two slots on the top are for welding recipes. If the player puts two items in there and presses the weld button the result will appear in the slot right under the weld button provided that the items are hot enough to be welded and flux is present in the bottom right slot. Welding consumes 1 piece of flux.
The slot that has a ghost image of a hammer is for a hammer.
The slot in the bottom-left is for the item that the player wants to smith.
The button with the image of a map is for selecting the recipe the player wishes to perform. Pressing the button with both the hammer and the ingredient present will show the recipe selection interface provided that the ingredient is hot enough.
The cards drawn will be displayed to the right of the inteface.
To learn more about smithing go here.