In the printing process, successive thin layers of material powder are laser-welded to each other. Parts are built up layer by layer, enabling highly complex external and internal geometries and shapes to be built.
There is no other process by which these geometries can be produced. Because the powder is fully melted, the resulting metal part (e.g. 316L stainless steel or Titanium alloy) is just as strong as regular parts from the same material.