How to make an automatic smelter
What you will need
To make this auto-smelter you will need 5 chests, 3 hoppers, and a furnace.
How to assemble
Put down two chests. Place a hopper pointing into the chests. Place a furnace on the hopper. Place a hopper pointing into one of the sides of the furnace. Place a hopper on top of the furnace. Place a chest on all exposed hoppers.