Just finished making a door strike plate out of aluminum for my son's bathroom renovation. It's an old home so I had to CNC a new plate because the door had settled.
Polished it with an RO-90 and a progression of grits. It was surfaced on a mill first and after the milling, I went through:
Platin - 500 grit, 800 grit, 1000 grit, 1200 platin, 1500 platin, 2000 platin
Then switched to Festool polishing compounds and a felt pad progressing from 5000 to 8000, 9000, and 11000.
It's a mirror finish on the metal now. Should look great with his chrome bath accents.
First photo is the original finish off the mill. Quite a difference from the final shine.