# What is happening here? Boolean modifier works *almost*

So I want to hollow out a spheroid. I redo the normals, extrude inwards, use p to separate the smaller spheroid copy, extrude its faces only outwards, move it into another layer, then use a boolean to subtract this from the original (big) spheroid. You see the result. It works almost.

Why not completely? What am I doing wrong? The smaller sphere's protrusions definitely go fully beyond the bigger sphere on both sides, inside and outside.

Here is the file for download: http://www.pasteall.org/blend/41696

• It would be easier if you added only screenshots instead of gif in order to make post clearer. One reason for bad results of Boolean can be flipped normals; enter Edit mode for spheroid and press Ctrl+N with all selected, see blender.stackexchange.com/questions/3606/…. You might want to upload this file for convenience. – Mr Zak May 4 '16 at 11:42
• Thank you, I already aligned the normals. I will upload the file momentarily – specialsymbol May 4 '16 at 11:49
• pasteall.org/blend/41696 Here it is – specialsymbol May 4 '16 at 11:54
• What was the original mesh like (before Boolean) ? As for now subtracted mesh has good amount of Ngons and inverted normals. If that was present while using modifier the result won't be expectable. Note: do you want to get effect of wire-like mesh ? – Mr Zak May 4 '16 at 12:21
• Before it was just a solid body with 12 faces. I used the answer from TLousky to get exactly what I wanted. No, it was not a wire-like mesh - it has to be solid (from all sides) to be suitable for 3d printing. – specialsymbol May 6 '16 at 9:32

You can do this with the new (blender 2.76+) intersect (boolean) feature.

Steps to recreate:

1. Go to edit mode (Tab).
2. Select all (A).
3. Extrude inwards (E).
4. Go to Face select mode (CtrlTab).
5. Extrude individual (Tools panel-->Add-->Extrude Individual) outwards.
6. Select entire inner mesh island (CtrlL).
7. Open dynamic spacebar menu (Space).
8. Type in "Intersect (Boolean)" and confirm.
• Thank you very much for the detailed description. It worked way better than what I did before. Oh, and it solved my problem :) I've been trying for five hours today to find a solution or workaround. Thanks! – specialsymbol May 4 '16 at 13:10