I'm extremely new to 3D modeling, just started today actually. But there have been some problems with the boolean modifier that I just cannot google my way out of. First, when I'm trying to carve out a chunk instead of making a hole right through an object, the two meshes just combine instead of subtracting. The second is when I finally get it to work it leaves my object a hollowed mess. In the screenshots, you can see the left object is the one I want to keep, and the right one is what I want to subtract from the left one. If I select Difference the objects just combine, but if I select Union I get what I actually want but the resulting object is hollow and with some weird planes all over the inside. How can I fix these problems?

I want to subtract the right object from the left one.

It should go completely through the object. I select Union because Difference just combines the two.

Here are the results, I cannot no matter what I try and with all the googling i can do get the object I actually want.

  • $\begingroup$ A comprehensive post on booleans can be found here: Boolean Modifier not working $\endgroup$
    – user1853
    Mar 3, 2019 at 18:24

1 Answer 1


You have the right operation i.e Difference, and it is working too, the problem with it is John Cena(you can't see it). Jokes aside!

You only can't see the changes because the object is lying on it. If you want to see the changes before applying the modifier, select the object which you are using for hollowing and go to Object Tab. Under View Port Display Select Display as Wire! Now you can see the hollow.

enter image description here

And also after applying the modifier you can delete that hollow helping object to see the hollow. But its risky, arrange it first with the above method and then you are ready to apply and delete.

Have fun!

  • $\begingroup$ Thanks for the answer, but sadly it doesn't solve my problem. In the third screenshot, I have actually removed the hollow helping object out of frame. I don't need to see the changes before applying because this is precise to the mm, but even so, if I display either object as wire or both, it doesn't change the results which are that Difference combines the two meshes, and Union leaves a hollowed mess behind. $\endgroup$ Mar 4, 2019 at 5:34
  • 1
    $\begingroup$ Can you attach your blend file? $\endgroup$
    – Yash
    Mar 4, 2019 at 5:38
  • $\begingroup$ @BaltasarLevíElíasson Difference doesn't combine objects, its just what your are looking for that is hollowing and Union is attaching objects. $\endgroup$
    – Yash
    Mar 4, 2019 at 5:40
  • $\begingroup$ See also blender.stackexchange.com/questions/131315/… $\endgroup$
    – Yash
    Mar 4, 2019 at 5:42

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