Can I use additive manufacturing to mass produce custom metal parts?

The answer is, it depends. If you are making small batches of a metal part for an application with technical requirements that meet the capabilities of metal 3d printing, then the answer is yes. For example, GE Aviation famously makes lots of fuel nozzles using additive manufacturing processes. Fuel nozzles are a fabulous application for 3d printing because there are no huge loads or stresses on the part, the shape is highly organic, and 3d printing means that the designer no longer has to make compromises on the shape of the part because of the limitations of the production process.

For other applications, however, additive manufacturing still has a long way to go. For low value, high volume applications, there really is no way for additive manufacturing to match the speed of common mass production techniques for metal fabrication. For weight bearing parts that need to meet stringent material property requirements, the output of most additive manufacturing processes for metal fabrication may not meet criteria. 

That said, there are multiple companies pushing forward with several different approaches for metal fabrication. We hope to see new additive manufacturing solutions that can enable the creation of more and more cost effective metal parts in the future.