Problem in making a closed polyhedron for 3D printing

I wanted to 3D print this geometry, which needs to have a closed polyhedron, for which I have baked this geometry in Rhino and converted its meshes into NURBS using the MeshToNURBS command and then joined them, but unfortunately it did not result in a closed polyhedron and I have no idea about what’s wrong with it. (1.2 MB)

I have checked the naked edges but they don’t sound like real naked edges

I can get a closed solid polysurface from your file by following these steps:

  1. Create a new Rhino file from template Large Objects - Millimeters.
  2. Open your grasshopper file and bake the 2 Custom Preview components.
  3. _SelMesh
  4. _ToNurbs (with Delete Input Objects option selected)
  5. _SelAll
  6. _Join

If you start with the Small Objects - Millimeters template, you get the results you show.

The problem is with the tolerance of your input geometry. I get a closed solid polysurface by starting with the Small Objects - Millimeters template and changing the absolute tolerance from .001 to .0011 before joining the surfaces (minute change, but in this case enough).


Thanks for your response Kevin. It worked and I was able to build a closed polysurface, but in the next step when I wanted to convert it to mesh ,Rhino was trying a helpless attempt.

I’ve a similar problem with 3 meshes trying to make in Grasshopper a closed mesh for 3dprinting
Any suggestion will be appreciated!
Thank you in advance!

ClosedMesh.3dm (80.5 KB) (123.3 KB)

What command and settings are you using?

Works ok for me just using the _Mesh command using the Simple settings set to the Fewer Polygons end of the scale.


You have internalized the geometry in your grasshopper file :+1: so there is no need to upload an empty Rhino file.

In order to join meshes together, their edges/vertices must line up.

You can see that the edges of the meshes in your file don’t line up:

These are the naked edges from the meshes you’re trying to join together:

  • Inner mesh has 266 vertices along its naked edge.
  • Outer mesh has 214 vertices along its naked edge.
  • Each edge of the ribbon you’ve made to join the inner and outer meshes together has 501 vertices.

I converted the 2 meshes you started with to breps and joind them with the connecting brep you made in your file and then meshed the resulting closed brep. This results in a closed mesh suitable for 3d-printing.

Edit: I used a couple of PufferFish components, since I saw that you were using it. (129.5 KB)


Indeed, no need for the empty Rhino file - I think it was a reflex…
It works well but as I’ve learned it is possible to transform a mesh into a brep I’ve decided to work only with breps and not to transform them again in meshes! Which is better for me!
Here is the result!
Thank you very much for your help!

Thanks, Kevin. I wanted to have meshes with small lengths of edges that made the meshing process take too much time. Finally by increasing the mesh edges length it was solved