The surfaces are the 3D geometrical elements used to construct the models. The surfaces are directly derived from importing the CAD models into Patchwork 3D Design. The surfaces are represented by a lattice of triangles (a mesh).
A surface may contain several non-contiguous geometrical elements.
The same surface, whether it consists of one or more geometrical elements, can receive only one material. It is therefore important to split surface elements in your CAD tool before importing them into Patchwork 3D Design.