EDIT: My Merchantmen can create steel, apparently. I had 15k steel and built 20 Merchantmen, which costs 15k steel. In their holds is 5k steel. Also, my damn Bulkfrieghters decided to come back with food, despite steel being the most profitable purchase they could have made - seems I didn't watch Kai/Vellos' Bulkfreighters enough before making my decision
My merchantmen probably aren't doing anything actually profitable. I don't much care. I just like having lots of trade ships scurrying around. Makes me feel all mercantile and !@#$.