General rule of thumb: the stronger and tougher the metal, the more work needed.
Think carefully about trying to retain the finish of a rolled stock or cast object as polishing processes can be very labour-intensive and may not be worth the investment.
Otherwise perhaps…
| Chrome plating | if you want a shiny metallic surface |
| Powder Coating | will give anything a good even coating |
| Spraying | a finer finish than powder, for retaining more detail or if your object is already finished well |
| Galvanising | industrial look, zinc plating, normally hot-dipped so creates a dripping or flecking – not a uniform finish |
| Patination | essentially chemically accelerated oxidation (weathering/corrosion); colour and surface depends on metal and alloys; protects the surface layer from further corrosion |