As far as polishing metal goes JesseIL is correct, a Dremel is worthless for that kind of job. It really depends on what kind of metal you want to polish and how much access you need to it to be able to polish it. However, for all of my polishing needs I always use a die grinder and some good flapper wheels. For this type of thing you would need a good set of flapper wheels 320-1000 grit, some WD-40, and some good old NeverDull, oh and a lot of time. Polishing metal is not exactly easy and is a very time consuming process, if done correctly. For something like the Fuel rail I would take it and clean it really well, next I would take my die grinder and go over it real well with a 320 grit flapper wheel and work my way up step by step all the way to a 1000 grit wheel, spraying down the piece wit h WD 40 between each sanding step. When all of that was said and done I would take the piece an put some NeverDull all over it and buff it out on a BenchGrinder. You can keep doing the last step until you get the results you desire. If you really want a mirror like shine then you can go through the sanding steps all the way up to a 2000 grit flapper wheel and I guarantee you that when done properly this method will leave you a mirror-like finish that will rival the finest polished products available.
