While 3D printing and additive manufacturing are increasingly being used in many industries, its use by CAD designers is not as common. Part of the issue is the additive systems themselves–there are features and capabilities that need improvement before they are seriously useful to the CAD designer.
Improvements are coming, so very soon, it will be common for CAD designers to use these systems, both for rapid prototying and low-volume manufacturing.
Ansys wrote a nice blog about the needs and challenges facing 3D printing/additive manufacturing for the CAD user. Take a look!