Been making a lot of suggestions but I just love this game
It seems to easy when making metal, because you can preheat the metal, to add a bit more difficulty you could perhaps make it so that the ingots could melt if left alone in the heat for to long, if thats how they work in real life, I assumed you studied up on forging when you made this game. The game seems to easy and some difficulty would be really cool. Just a though :)