There is a wide range of materials are available: ABS, PC, Teflon, Nylon, Peek, Ultem, Aluminum, Brass, Copper, Delrin, Magnesium, Mild Steel, PMMA(Acrylic)…etc,
Regarding surface finishing for CNC machined parts, it is an extensive options available: anodizing, polishing, sandblasting, painting, powder coating, printing..., or mix of them.