How do I get the smelting arrow that usually appears in the vanilla furnace?

So I'm kinda new to making gui's and i want to make something that's called a purifier, and will display the amount of ticks it needs to purify before giving you the item as an arrow, kinda like the furnace. Can anyone help me as I looked up as many tutorials as i could, but couldn't find what i was looking for. Thanks in advance!