Could it be possible to allow items to stay on the anvil after modifying them with the hammer? It's a matter of smoother workflow. In other words replace the modified item with the output item as an option. It would help a lot specially when you are trying to combine a bunch of books or similar things.

This would stop the tedious process of having to find the item in your bag to re-add it to the anvil to re-hammer it.

Actually never mind that. After playing with it a little bit more I realized how to work it.