All good information. But i want to point out a significant, IMO point.
Look in your book, figure out what you can work, and get a set amount of ignots of each of them (I like 10, round numbers, when i did this) and then note your PPs and exp level, and melt and cast 10 copper, lets say, note whether you get 10 practice exp (need to be trained) or 20. (some get it while melting, some while casting, and some, both) as well as the amount of PPs you get. repeat this with all of them, then you can calculate exactly how much practice and PPs you get per each one.
This system works with comparing mines, comparing weapons (time it takes to kill a given mob, or even amont damage difference between Q50 short sword and crafted one). or any other similar questions. I find it is better to experiment what works better for you. Theoretically, your character MIGHT get more PPs point working bronze than steel, even if someone else gets more working steel. That being said, since mentioned above, I like using steel to train, good practice and PP, and can reuse it to craft weapons later. Bronze and iron can only be used to make shields so far AFAIK.
