Shiny shiny stuff

You need more elbow grease to get to the smooth surface. Nothing is impossible - it's just sanding down to get the even surface without any pitting.
Just go over it again and again like crazy. Use some wire wool.

I've done the same with chromed risers yesterday. They had some deep scratches around the mid section. As they're aluminium, I decided to remove the coating altogether with dremel (with the wire brush mounted). Dremel left some rough bits on the curves, but I got there with various grit sandpaper - it just takes longer. Autosol and a cloth - looks shiny as dog's bollocks.

I think you mean polished aluminium, not chromed.