Avoid mistakes that occur when designing 3D files for 3D printing on Blender

The following are common Blender repair tools. Some repairs will still need to be verified or performed manually.


  • 1.1. Preparing the Software
  • 1.2. Polygonal Modeling for a 3D Print
  • 1.3. 3D Printing Modifiers: Best Practices
  • 1.4. Case Study: Creating a cat’s head
  • 2.1. Importing into Blender
  • 2.2. Verification Tools
  • 2.3. Export Your File for 3D Printing
  • 3.1. Double Verticies
  • 3.2. Inverted Faces
  • 3.3. Non Manifold Meshes
  • 3.4. Non-Planar Faces
  • 3.5. Isolated Vertices and Faces
  • 3.6. Acute Angles
  • 3.7. Fine Parts

In edit mode, use keyboard shortcut Ctrl + V and choose “remove doubles”. This action will remove inadvertent double vertices, which can cause issues during a 3D print.

Accessible through the shortcut Ctrl + N in edit mode, this action will recalculate the selected faces outward, alowing the 3D printing software to recognize the volume of the object.

To select the edges of non-manifold mesh, use the Addon “Print Tool Box” or select “No manifold” in edit mode.

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Then by hitting the F key, the empty parts will be filled automatically. Warning: this mode may create Ngons (faces with more than four vertices).

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It is possible to use the function GridFill where the vacuum portion will be formed by an even number of vertices.

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The non-planar faces are generally quads (faces with four edges) or Ngons (faces with more than four edges) that have too much internal angle. These faces are often seen as non-printable by 3D printing software. Use the add-on “3D printtoolbox” to select the “Distorted” faces. Then in Edit mode, in the header of the 3D viewer, use Mesh / Clean up / Split non-planar faces. Blender will generate triangles instead of quads. Please note that this action is irreversible and changes the topology of Quads to tris.

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Isolated vertexes and faces ought to be excluded from the model. These are often forgotten remains of a model which was not finished. They need to be deleted because they are volumeless parts of the model, which are not printable. To remove the isolated pieces of the mesh, use the add-on “3D PrintToolBox”, click the “Isolate” button, then “Cleanup”.

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Sharp bends in 3D printing are problematic because they create parts that are too thin to be printed. After you locate an acute angle in Edit mode, it is possible to use Addon 3D PrintToolBox to select the problem part. Then use the “Smooth” tool in the Special menu (shortcut W).

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When a part is too thin to be printed, it is possible to thicken the general size of the object to thicken the problem zone.

If you’re looking to thicken just the part of the model that is too thin, there are a couple of solutions that are possible. Most of the time, a Scale along the normal with edit mode activated will suffice.

Here’s an example of a hand with fingers that are too thin to print.

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It is also possible to “stick” the parts that are too thin to a thicker geometry. You must fuse the geometries such that they will not create superimposed surfaces, however.

Example of a hand stuck to a character.

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