Basic design was from someone i cant remember (off you tube, hopper tutorials i think)
i'm not claiming this is all my work i just increased the furnaces to 28 and made into a huge factory and wanted to upload so that others can put into their worlds if they want
when importing, you must access the 2 timer hoppers in the left and right wall (go in the main door, then 2 doors left and right), and put 1 of anything in 1 of the hoppers, (to start the timers, these are what enables the fuel and stuff to be pushed up to feed the carts), also you'll need to place 2 chest carts on each of the starting positions at the top (you'll see through the glass), (reason for this is that schematics dont save stuff in hoppers/chests or things like carts, just blocks), these would only need to be done once
when you go in the door, place fuel in the left hand side chests, stuff to cook/smelt in the right chest and then wait a little while for it to be transferred to the chest carts, then press the button and it starts to work, under the button is a chest that will appear all the cooked/smelted items
CREATIONS
MINECRAFT-SCHEMATICS.COM