We have an HP 3D printer at work for making prototype parts to check fits and visuals. It prints small "blobs" of molten ABS plastic which stick to each other. The parts aren't very strong, they are very porous (like sintered metal) and the surface finish isn't very good. It all depends on what you want the parts for/to do. If they are visual parts only and don't have a specific function then they would probably be fine. Any strength requirements or sealing ability then forget it. They are also very slow to print so probably aren't cheap.