If you needed wood or metal, it was not on sale.

The polyspherical head needed less metal and was narrower due to using only one rocker shaft.

Once it's used all the spare iron in the trunk, it'll need fresh metal from somewhere.

Couldn't they have come in and said, "We need metal.

I need metal, that's all there is to it.

"We need metal to repair the engine, and all our scrap was lost in a lake of dust."

Even to broadcast a radio signal we need metal.

"So if hoverboards need metal, how do they work on the river?"

If you need metal, you start with ore.

You tell Tarzak mat in exchange for those planks and poles, we're going to need metal.