There's something off about this screenshot in my opinion:
You see how the casing has wood, but most other copper blocks don't? The andesite/train casings don't have that problem as you can see:
So I decided to add some much needed wooden details to the copper textures, and it looks kinda cool.
So that's the resourcepack, it's a bit simple, but it was quite fun making/editing a couple of textures. I also didn't touch the insides of fluid-based blocks, since it makes sense for that to be 100% copper.
More images in the gallery.