NAFTA & Duty/Taxes

It occurred to me last night... does NAFTA cover art? Like, if I want to send a painting of mine to a friend in the US, and want to write down a decent sized value on the declaration form so that I could pay for a corresponding amount of insurance and not seem suspicious... would my friend get dinged for duty on the gift? Or, since it's of Canadian "manufacture", would that mean it's covered under NAFTA? I have something I've been working on for a friend for over a year now, and, although I do plan on wrapping it securely, I want to be compensated should it go missing or get damaged when I finally am ready to mail it. (Given that it's art, it's a bit hard to value, but I'd price it based on what I think I could sell it for in one of my art shows.) However, I don't want my friend to get taxed out the wazoo for something (s)he doesn't even know is coming. Does that make sense? I wonder if I would need some special forms or something...