I didn't say they were.

"I could be wrong, but I don't think metals can be replicated, only mined."

But imagine the alloys

For additional context, alloys are a mix of two or more metals or elements.

Who knows what could be possible beneath the surface using artificial substances in creation of new alloys? Moreover, who knows how efficient such a process could become if you could use, say, a quarter of the metal content in an alloy with other substances?

There are new alloys discovered or created somewhat infrequently even today, so even with full metal alloys there is a lot to be discovered.

There are also alloys of thermoplastics.

Then there are potentials for composites.

The sky's the limit.