There are party bags that have metallic paper. you might have to search for copper.
I have kept my Legos in one big box. Everything is still there. These are one of the two things of my childhood I will never let go (the other being Kenner Star Wars action figures, of courseI have half a bureau full of LEGO parts. I hit tag sales and purchased some of bags of really cool shape legos for $5 bucks a garbage bag full. People tossed them when their kids went off to college. I've got awesome tracks, hinges, all the really weird parts that allow for making crazy stuff, which my son and I did for 4 or 5 years.