Scrapper rank 1 gives you copper from scrapping modified weapons, such as modified pipe rifles and pipe pistols you find as you wandering around. As to a factory location, well incase you don't want to know it I make a spoiler for it.
I also found that using the "tracking" system helps me a lot getting resources that is in short supply, actually have over 100 adhesive right now, and I have not made a single Vegetable Starch yet. not figured out how to track an item if having any already, part from removing them from workbench and putting them into a container or follower. Hopefully there be a mod that lets you use track function even if you have a few in the workbench.Watt's Consumer Electronics has quiet a bit of junk that contains Copper, maybe not a boatload though.
Yeah I have both the scrapper perks so things I've marked for search light up. It's more annoying than anything as I usually forget to unmark things. I'll head to that location, cheers!