When the internal cut features of a model are of most importance in a design, one approach is to create solid features that represent the negative space of a part. Once the negative space is complete, the Combine command can be used to subtract the volume from another solid body. Use solid geometry representing the interior space of a manifold to create the negative space of the part. Create a separate solid body surrounding the geometry as the main body of the manifold. Combine the solid bodies in the part using a subtract operation.
