The biggest advantage of engraving, milling, grinding or other methods that allow material to be removed from a block of raw material is the preservation of its original properties. Unlike plastic processing for example, which is based on deformation only, here the basket of possibilities is much wider.
Another advantage is reflected in precision, the machines that exist today are based on the use of computers, which allow a combination between automation and an optimal level of accuracy. This way you save on expenses without compromising on performance and work according to the original specification that comes from the client.