Minecraft wiki entry for Shelters, associated text: This room is important if you are a big miner and/or adventurer as you can smelt large numbers of ores quickly. Make a large room and line the walls with furnaces, possibly keeping a chest of fuel such as coal or wood planks inside as well (A bucket of lava is very good too. It can smelt 100 items and also is a good source of light.). The benefit of having multiple furnaces is a faster overall smelting time, since each furnace is able to run independently. Having each furnace full of said fuel is also helpful. This room could easily be merged with the Crafting Room, and it may be most convenient to do so. Also, bear in mind that you can use hoppers if you wish to automate your smelting operations.