I have this .stl that I downloaded and I need to create a solid of this 3D. However, if I click "Make solid", it doesn't work.

How can I do? I think the problem is the black layer but I don't know how to resolve.

Before make solid:

Screenshot of Meshmixer - before make solid

After make solid:

Screenshot of Meshmixer - after make solid

I need to make solid and the black layer is deleted when I do it.


PS: The other object are different item, so if they are there or not is the same

  • $\begingroup$ Hi and welcome. We may require more information, please edit and add more details. $\endgroup$
    – Greenonline
    Jun 19, 2022 at 13:39
  • $\begingroup$ Other? I have download the file, I don't much more but I need to make solid and the black layer is deleted when I do it $\endgroup$
    – Inuraghe
    Jun 19, 2022 at 14:46
  • 1
    $\begingroup$ Do you have a link to where you downloaded the .stl file from? If we can reproduce the issue, then maybe a solution can be found. Please edit and add the link to your answer (don't add info in the comments). $\endgroup$
    – Greenonline
    Jun 19, 2022 at 17:44
  • 2
    $\begingroup$ Your object browser shows three objects in the first image, only one in the second. Are the missing pieces those of the other two items in the first image? $\endgroup$
    – fred_dot_u
    Jun 19, 2022 at 18:08
  • $\begingroup$ The other two objects are different item $\endgroup$
    – Inuraghe
    Jun 22, 2022 at 7:01

1 Answer 1


Make solid requires an enclosed volume

To run the make solid operation, the selected parts need to enclose a volume. In case the volume is not fully enclosed, the program tries to solve a solution that closes the open surface.

The black layer is most likely failing to compute because its normals are flipped. This means it does not enclose a surface, it excludes anything between the surfaces from being inside the body defined by it - it is everything but. This is solved as "this surface does not enclose anything, so I cut it out" but for where it creates a valid solution in the area of the white surface before the operation.

This leaves you with the white retained part after the operation.

To fix this is an in-depth project

Fixing such errors is quite involved. You will need to do the following steps, depending on your program to alter:

  • flip the surfaces so that it shows outside
  • make sure that the body is closed, possibly by adding missing surfaces
  • $\begingroup$ How can I enclose volume? $\endgroup$
    – Inuraghe
    Jun 22, 2022 at 13:09

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