Before mass production, customers usually to make a prototype first to test or verify their design, and the prototype needs different surface treatments according to variety functions.
Mechanical spare parts and products for inner structure usually don’t need precise surface treatment;
The outer cases always need special surface treatment for beauty/ protect it from air, sun and rain.
Generally what we can provide are as follow:
Plastic: Polishing, Painting, Silk-screen, Electroplating, UV coating, Laser engraving, and so on;
Metal: Polishing, Mirror polishing, Painting, Anodizing, Blackening, Powder coating, Electroplating, Passivating, and so on.