How do I create the top Face without it covering the "holes"


I am trying to make this model to 3D print.

But whilst the model in the pic looks good, Its broken and solid inspector throws up a ton of error.

In creating this, I got to this point with no issues:

But when I draw the rectangle to close the top surface this happens:

I assumed I would be able to just select each of the C shapes and delete them, but selecting them highlights the whole top surface.

I am sure this is all about “intersection”, but I have tried “Intersecting” faces over and over and it doesn’t help… I have intersected the the WHOLE model and it took about 1 hour to complete and when finished and it looked good (See the result at the very top of this post) but its still broken.

This kind of thing always catches me out and I have no idea how to fix it… How exactly can I create the top layer over this model in a way that the cutouts are able to be selected and deleted?

I have attached the file incase you want to take a look…

5. Example for Forum to ask for help.skp (461.2 KB)

Thanks in advance for your help



The curved parts are Components.
• Explode them.
• Retrace one edge of the box with the line tool to create a face over the entire top of the box.
• Right context click on that face Intersect Faces > With Model
• Delete the unwanted faces.
• Correct face orientation where needed. (white side facing out)
• Now select all the geometry and make it a component.


Here’s a moving version of what @Geo described.


Thanks both… Thats HUGE help

I “intersected” the faces which worked just fine… But watching the animated sequence gave me a tip I never knew (where you draw along one edge of shape) so will try that in future

I really appreciate your help.



Another way with an extension (FixIt) to speed up the cleanup process that I often use in such a situation …
(But make sure you know the manual way too :wink: )


If you want to keep them components:

  1. You can make them into cutting component, then explode it.

  2. Alternatively, you can drag a cutting component from the components box onto the surface, then copy it.


Awesome… Will check out “FixIt”… That could be just what I am looking for, for other issues I have seen.

I use SolidInspector which helps, but not always, so it will be interesting to see what FixIt makes of some of the issues.



Yes, it’s always good to have different options…


There’s also a handy plugin called “make face” that will make faces of coplanar geometry that has for some reason failed to heal/connect, it can save a bit of time retracing edges, by selecting the whole top face it will heal those sections ( make faces of them). each can then be deleted individually, or you can select the outside area and then shift click the whole face to invert the selection and delete them all at once.