It's said that 'there's nothing new under the sun' and in this case it applies as well. It's already been done.
Copper is soft, machines easily and polishes well. However, it has this nasty little habit of oxidizing. You might find a finish that holds off the oxidation for a period of time but the wrong finish can cause it to turn green rather quickly. Have you ever seen a house with a copper roof? Just a lovely shade of green. You might also be mindful of the woods, etc. that the copper is partnered with. Incompatibility can initiate a reaction with the copper and hasten the oxidation process even without oxygen being present. By all means, keep it away from aluminum; galvanic reaction. The copper and aluminum will dissolve each other. This may be due to their electrical charge. One being positive and one being negative. That's not real pretty either.
I'm not trying to dissuade you from your endeavor, just bringing to light some of the consequences you might experience.
