For that map layout, it could be interesting if only the lower sections actually gave metal output. Give a few small patches up top just to give people a chance if they get ran out, of course, but the sweet sweet metal brew would work well down below...
Well It is important to tell someone when there work is good!
And there are to many people in the habit of going "why could you have not done this or this" and I like to be more positive.
However after reading all teh coments I reckon you dont have to worry about that.
Quick question, did you set the shadows as to be realy dark on the metal heck map, or is that just because the ground is so dark anyway? The way its lit... Makes it look almost supream comander.