Okay, so the D20 Blackmoor Sourcebook introduced the idea that Metal and Wood are Elemental Planes, just like Fire, Earth, Air and Water.

They also had things like Metal Elementals and Steel Mephits from the Elemental Plane of Metal.

Now how could this plane be more than just a source of a couple of monsters and perhaps a place to travel for extremely powerful characters?

I'd like to bring the Plane of Metal into a more regular campaign. Maybe something like an elemental node or a gate from that plane into the Prime Plane?

Or perhaps more an artifact. A forge perhaps that taps directly to the Plane of Metal?

However, the Elemental Rulers of Metal are unhappy about this forge existing. Possibly this forge was created during the ?

Perhaps Metal Elementals and other creatures are still searching for the Forge?

-Havard

But... isn't metal just... highly refined Earth...? :|

Let me be THAT ONE:

https://www.youtube.com/watch?v=qwstSzSEbGk

Don't know if you've read Jim Butcher's (if you haven't, you should!). In it, most of the characters are attuned to one or more elemental spirits tied to either water, earth, wind, fire, wood, or metal (a fury) that allows them to do all sorts of nifty things. With a powerful enough fury -- which seems to be linked to familial bloodlines and such -- wind furycraft allows one to fly, for instance. Roads built with earthen furycraft allow faster travel (especially if those traveling also have an earth fury). Arrows loosed by those who practice wood furycraft fly further and hit harder, as they can flex their bows beyond normal limits. Watercrafters can heal all but the most grievous of wounds, or reshape their features into the perfect disguise.

And if you know metal furycraft, you can do things like enhance arms and armor (aligning the matrices). Two metalcrafters going toe to toe is truly a sight to behold, especially when one "goes nova" and turns his skin to steel. (A hugely painful process, but then, metalcrafters can also use their craft to dampen pain, if I remember right)