How to take cut out mass from one object using another?


I have 2 objects. One is a big cube and one is a small cube (50% the size of the big cube). I have placed the small cube with in the big cube. Now what I would like to do is to make the small cube become an inner cavern with in the big cube.

What I mean is that I want to use the small cube as a sort of 3d eraser and take away mass from the big cube so that a small little cube room is left inside.

How is this possible?


The Boolean Modifier.

Note that booleans can give a messy mesh that may need some manual cleanup depending on your final use.



Will the cavern have an entrance? If so what type?

  1. Add Cube
  2. In Edit Mode select all vertices of Cube
  3. Press to E to extrude and hit Enter
  4. Hit S then type .5 (50%)

This creates a hole in the middle of the cube with normals pointing inwards.

I have attached one for you to see. It has a camera, lamp and sphere inside.
Just hit F12 to render.

If you need more help modelling an entrance let us know.

Hope this helps?

Kindest regards,



Cavern 001.blend (205 KB)

ahh no my friend, the idea was to make a cavern with out an enterance . i know the extrude technique. you see, what i really want to do is to be able to place a camera & light with in this cube cavern and render the inner walls. any ideas?

thanks for that RM, but can it make a closed cavern?

Please study the .blend that I attached to my first post. It is a cube within a cube
no entrance. Inside you will find a Camera/Lamp and Sphere the render it produces
is of the inner walls…

So ahh yes my friend.:wink:

Kindest Regards,


You don’t really need to cut out the shape inside the cube for that. If you’re not planning on making any holes or windows to the outside, just flip the normals of the cube, and place camera + lights inside

interesting, but what is a NORMAL and how does one flip them?


Wow. OK…

caeious, I’d suggest you read up on some of the blender help files and tutorials. Learn the basics and everything will come together much more easily.

Just think of the normal as the direction the face is pointing. To flip it select the face and press W. There is an option in the list to flip normals. Also in edit mode under the Editing (F9) / Mesh Tools More is the option to draw the normals on the object.


Aah yes, solids-based modelling, I remember that from calligari truespace…and various CAD programs.

Boolean operations were mentioned above, that is what you are asking for.

make sure you are not in edit mode (make sure both cubes are that pinkish purple color.)

Select the smaller cube, then hold the shift key and select the larger cube.

press space bar, select Object->Boolean from the menu.

in the next menu, select Difference (subtract)

This will leave you with 4 cubes. 2 smaller ones and 2 larger ones. (It preserves your original object) However, one of your larger ones will now have the cavern you were seeking.