We had a brief encounter with Alexander Lobovsky, P.E., who is a partner with United Materials Technologies of New Jersey. Lobovsky's company is developing a new method for smoothing 3D metal prints.
The problem with metal 3D prints is the same as plastic: printing by layer causes visible ridges on the object. These can be larger or smaller depending on the technology, but are always present. Metal parts are particularly vulnerable as people are used to seeing (and touching) smoothly casted/forged/cut pieces.
Lobovsky's technology somehow manages to smooth out these ridges successfully, as you can see in the image above.
The most common method of smoothing parts, both plastic and metal, is simply to toss them in a tumbler containing an appropriate abrasive and they'll smooth out. However, this approach doesn't work for all objects. We believe Lobovsky's technology may be able to address many more geometries.