AM starts with arranging different layers. If manufacturing problems arise due to the arrangement of layers, these problems cannot be solved by developing methods to convert the arrangement into parts. It is given how manufacturing problems arise due to the layer arrangement. The problems are basis to divide AM into two categories: one category, where there will be problems because the problems are not solvable, and another category, where there will be no problems because the problems are solvable. The problems are solvable not because methods are given on how to convert a layer arrangement but because methods are given on which layer arrangement to convert.