The process, in theory, is relatively simple. Take one 3D CAD model,

which shows the details of the design of the part, and split this up into
constituent layers, or ‘slices’. Next, deposit an initial layer of powder
onto a Z axis movable table.

 The individual particles of powder are then selectively fused by a
scanning laser according to the segmented CAD design, and the table
is dropped down by a minute amount for deposition and fusion of the
next slice. Upon completion, excess powder is then vacuumed away
leaving only the fused material. In this way, an intricate 3D structure
can be built up layer by layer.

Layer thickness varies depending on machine, but generally ranges
from 20-80μm. Parts are accurate to approximately 0.1mm in 100mm
and the smaller the build volume, the greater the accuracy.
Fiber lasers allow for an accurate melt, producing approx.
100% dense structure. There are a wide variety of metals
that can be processed in this way, including stainless steel,
titanium, aluminum and Inconel.