A 23 Wagon Bot based, fully beaconed and moduled smeltery, including iron/copper switch.
The constant combinator at the very right can be switched from 1 iron or copper plate to either, which then sets the request amount for the smeltery chests and wagon requesters.
Edit 12 hrs later: The switch doesn't work. I'll have to redo it.
2nd Edit: Fixed the Switch from iron to copper.