- Volume: the mesh must be solid. It cannot have holes, 2-point polygons or single sided polygon surfaces.
- Mainfoldness: the mesh must be completely and perfectly closed. The mesh must be “2-mainfold”: every edge must belong to 2 faces (not 1 or 3: only 2). Here are some reasons why a mesh cannot be 2-mainfold:
- Holes: Automatic hole-fixig can be made with Meshlab (Edit-Fill hole) or Netfabb; in Blender, from version 2.63 just selecting the vertices that “compose” the holes and pressing F in Edit Mode the missing face will be created.
- T-Edges: an edge cannot be on a board. In this case, the volume is considered open, even it seems closed. The face must be deleted and rebuilt (with the same method for closing holes).
- Internal faces: internal faces must be deleted, because they make the mesh “3-mainfold”.
- Minimum wall thichkness: tipically a wall thickness of 2.5mm is required. The Blender toolkit can show the too-thin areas, that must be scaled till a proper dimension.
- Polygon number: with too few faces the figure will lose detail, but with too many faces the fill will be heavy and possibilities of error will increase. To reduce the number of polygons of a mesh we should use MeshLab, following this tutorial.
- Intersected faces: there may be 2 or more faces intersecting themselves, expecially in objects composed by two or more meshes. Even in this case, a solution should be remove the intersecting faces and then closing the hole with the method said.
- Zero volume faces/edges: faces/edges with no volume.
So, here you can find the .stl file of the mesh. It's a really complex mesh, with an enormous number of faces and several problems (thickness, distorted faces); our goal is making it 3d-printable, and that's why we ask for your help.