I've created a little enclosure for a project in sketchup enter image description here

I then exported the .STL

When I open it in Creality slicer 4.8 or Cura 5.0 It looks like this enter image description here

I thought that the red was "overhang that needs support" (but can also mean a shell?)

Hoever, that's not the irritating part. That would be the grey in the middle where the "hole" should be.

When I slice it, it looks like this: enter image description here

I didn't notice this before I started printing and 4 hours into the print I noticed that it was just completely ignoring the window and was considering it as a part of the base.

Why is it doing this and how can I fix it?

I've tried editing the original sketchup model a number of times, but I keep getting the same result.

I read the question and answer at Empty space in model is getting filled but I'm not 100% sure that this is the solution I'm looking for.

The slicer, knows enough to see that the hole should be there, as it is rendering in a shaded area. It feels like there is a setting or some such that is "print the shaded area" with a checkbox (on or off) - and if that setting is there, someone please tell me where to find it!

I've also tried importing the STL into other programs (like fusion 360) and RE-exporting the STL, but the issue persists.

Please note that this question seems to be similar to mine, however, there isn't an accepted answer. The one provided below is actually a much better answer.


3 Answers 3


Use Solid Inspector to fix problems

Before exporting your Sketchup model to STL use Solid Inspector. It is available for free from the Sketchup extensions page and will detect reversed faces, stray edges, surface borders. The "main problems" mentioned above are then eliminated.


Sketchup is known for creating print-preventing problems of this nature.

Consider to run your STL file through a checker that will determine if the model is manifold or has self-intersecting faces. One can use Meshmixer feature, Analysis, Inspector, or also Windows 3DBuilder, which will perform a repair if desired. It is possible that the repair will result in a filled space, however, which would require editing in the original program.

  • 1
    $\begingroup$ The online version of Sketchup has this capability built in, just not in the free tier. It is called the 'Solid Inspector'. This inspector would have caught the issue in the original post, as I believe the inner edge of the hole to have reversed faces - like another commenter on this thread mentioned. $\endgroup$
    – Joris
    Jul 20, 2022 at 10:52
  • $\begingroup$ Thanks buddy, was looking for the "free option" though. I think @astPace got it though, It IS free as an extension in the extension warehouse. $\endgroup$
    – Jim
    Jul 21, 2022 at 21:56

The main issues with Sketchup are making sure the inner and outer direction of the surfaces are correct and deleting internal surfaces made by Sketchup, that shouldn't be there. My guess is the filled in hole in the middle is due to a setting in the slicer to fill in inner surfaces.


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