The four simple steps are:
Make a pattern
...in clay, MDF, rigid foam or plasticene
Form a mould
...in latex rubber (brushed) or plastic sheet (vacuum formed) - PVC, Styrene)
Cast a product
...in liquid plastic or polymer cement and
Coat it
...in metallic powders (gold, silver, bronze); specialty powders (crackle, distress, marble); interference colours (peacock, oyster shell) or water-based paint with a variety of pigment powders