I used a couple hand files and some sandpaper on my fixie.

Worked fine, looks good, but don't get carried away-- there's a (very) slight depression in the top tube where the file went a bit deep.

I bought the widest, flattest hand file I could find, hoping to avoid any unintentional ruts.

After sanding with 150/230/400 and priming/painting/clearcoating, it looks fine.

The paint-- Rust Oleum High Performance Enamel-- really blows. Least durable spray I've ever used.