there is no way that can be true.?? there have been numerous references to metal bending in episodes (see above comments) and in "the guru" episode.?? the fire nation specifically heats up and properly smelts thier metal to prevent metal benders from tearing them a new one.?? i will admit though i'm curious if toph can still metal bend fire nation metal.?? she is even more unique than other benders so mabye she still can because of the way she sees.?? that uniqueness can't have been forseen in firenation smelting processes to prevent metal bending.

??

a better question though.?? why metal bend when you can diamond bend??? in the "crossroads" episode aang covers himself with gems that are laying around and the mini tent to enter the avatar state.?? isn't it then possible to bend the hard known substance and launch it at various things or do major damage??? are the impurities there?

Ugh... people don't get it...

It has been PROVEN that the only way to metalbend is to locate the bits of earth left in the metal, and then bend those in order to force the metal into a shape.?? Metalbending is??impossible by anyone who doesn't have Toph-like detection or a radar.?? In fact, considering how Toph's parents treated her, Toph is probably the first metalbender ever, and is most likely the first to be recorded even by mouth.?? There are no other metalbenderas in the world as far as anyone knows, and Aang's comment was his wishful thinking.?? Toph might be able to teach Aang metalbending if his Avatar powers will allow him to sense the impurities, but no other earthbenders will be able to learn.?? (Unless they are born both blind and an earthbender and with Toph's unique power, which is about one in a billion or so.?? The odds are just a guess, though.)

It's this simple(I'll use a basketball analogy):

Take Kobe Bryant and ask him to drain a couple jumpers. No prob for Kobe Kob. Now blind fold him and spin him around a few times, then ask him to drain a couple jumpers. Big prob for Kobe Kob. But, take the blind folded Kobe, put him at the free throw line, tell him he's at the free throw line, what direction the goal is in, then let him shoot. He'll make a couple, probably sink them all once he gets a feel for it. The lesson? Once you know something is there, you stand more of a chance on affecting it even if you can't actually see it.

Toph knows where the impurities in the metal are and is physically targeting those, but if someone were to tell you, "You're not trying to bend the metal, but the impure portions of it." I don't see any reason why they wouldn't get the metal to move for them. Maybe not as well as Toph, but still...