One of the issues facing 3D modellers is the ability to create models perfectly suitable for 3D printing. A correct visual appearance does not mean it will print correctly, because the design might be ambiguous, have non-printable shapes or be "leaky" (non-watertight). Shapeways writes:
I've found that it's often difficult to retrofit your existing models for 3D printing, so it's best to start from scratch and with each step keep the goal (3d printing) in mind. This is especially true for models that you find online in model libraries - these are often made for visualization, not for 3d printing. Fixing these for 3D printing will make you want to pull your hair out!
Blog Casainho EMCRepStrap "About my RepStrap 3D printer based on RepRap and using EMC2 on GNU/Linux" had these non-manifold problems and found several useful resources to assist the repairs:
- Shapeways on Fixing Non-Manifold Errors
- Shapeways Video on Fixing Non-Manifold Meshes
- Shapeways Tutorial on Fixing File Errors
- The Meshlab open source system for processing and editing of unstructured 3D triangular meshes
- The Lucid Ubuntu package for processing and editing triangular meshes