# Merging vtkpolydata and vtkpolydata issue / Add vtkpolydata to vtkpolydata failed / vtkBooleanOperation failed resulting in non-manifold
**URL:** https://discourse.vtk.org/t/merging-vtkpolydata-and-vtkpolydata-issue-add-vtkpolydata-to-vtkpolydata-failed-vtkbooleanoperation-failed-resulting-in-non-manifold/8191
**Category:** Support
**Created:** [April 1, 2022, 3:15am UTC](https://discourse.vtk.org/t/merging-vtkpolydata-and-vtkpolydata-issue-add-vtkpolydata-to-vtkpolydata-failed-vtkbooleanoperation-failed-resulting-in-non-manifold/8191 "2022-04-01T03:15:59Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@hye00525](https://discourse.vtk.org/u/hye00525)
#### Post date: [April 1, 2022, 3:15am UTC](https://discourse.vtk.org/t/merging-vtkpolydata-and-vtkpolydata-issue-add-vtkpolydata-to-vtkpolydata-failed-vtkbooleanoperation-failed-resulting-in-non-manifold/8191/1 "2022-04-01T03:15:59Z")
Hello,
I am trying to add cone-shaped or triangular pyramid-shaped vtkpolydata fins to vtkpolydata at specific positions in polydata. (like picture below )
I plan to print this stl using 3d print, and I have tried the vtkBooleanfilter, but failed to print due to the non-manifold issue, so I am asking if there is another good method.
My trials-----
- Merging two vtkpolydata using vtkAppendfilter → 3d print was not possible (It looks like it’s merged, but is impossible to print because the vertex and face are configured separately)
- Merging two vtkpolydata using vtkBooleanfilter: 3d print impossible due to **non-manifold creation** (same issue as [this person]([https://discourse.vtk.org/t/the-result-of-boolean-operation-returns-non-manifold-surfaces](https://discourse.vtk.org/t/the-result-of-boolean-operation-returns-non-manifold-surfaces) /4018) )
- Using Ronald Romer’s vtkbool library: Since my project uses vtk-9, it was difficult to build and use. (Note [https://github.com/zippy84/vtkbool/pull/37](https://github.com/zippy84/vtkbool/pull/37))
Has anyone tried a similar approach?
Any advice or code example would be great. Thank you.
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### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [April 2, 2022, 1:55am UTC](https://discourse.vtk.org/t/merging-vtkpolydata-and-vtkpolydata-issue-add-vtkpolydata-to-vtkpolydata-failed-vtkbooleanoperation-failed-resulting-in-non-manifold/8191/2 "2022-04-02T01:55:48Z")
We have updated vtkbool to work with latest VTK master and fixed up its Python wrapping. It works very nicely, both in C++ and Python. It [can deal with fairly complex meshes for creating 3D-printable surgical guides](https://github.com/SlicerIGT/SlicerBoneReconstructionPlanner#screenshots):
[ ](https://raw.githubusercontent.com/SlicerIGT/SlicerBoneReconstructionPlanner/main/BoneReconstructionPlanner/Resources/Screenshots/screenshotPatientSpecificSurgicalGuides.png)
The modified vtkbool code is available [here](https://github.com/PerkLab/SlicerSandbox/tree/master/CombineModels/Logic). We have not pushed our changes back to upstream because we are waiting for @jcfr’s VTK remote infrastructure to be ready. Until it is ready, you can use vtkbool in Slicer’s GUI, or in the virtual Python environment that Slicer provides, or in C++ Slicer modules, or (as a short-term workaround) just copy the files from our repository and use it in your C++ project.
At some point there was also a vtkbool Paraview plugin, but I don’t know if that is still available.
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### Author:  [@hye00525](https://discourse.vtk.org/u/hye00525)
#### Post date: [April 2, 2022, 6:30am UTC](https://discourse.vtk.org/t/merging-vtkpolydata-and-vtkpolydata-issue-add-vtkpolydata-to-vtkpolydata-failed-vtkbooleanoperation-failed-resulting-in-non-manifold/8191/3 "2022-04-02T06:30:32Z")
Thank you very much for your detailed explanation and code.
I’ll try it. Have a nice day!