how to make hollow mesh?

[jabeds]

I have just uploaded my first mesh build from blender. Its a hollow shape but when your inside it is see through, can someone help me?

[Rahkis Andel]

Add a solidify modifier. It should have a thickness property to...well, define the thickness, of course.

The problem is that SecondLife will not display the backside of a face. The back of the face is the direction opposite of that which the normal is facing.

[Rolig Loon]

Mesh does not have an "inside".  If you want one, you have to create a second "outside" facing inward.  You can do that, as suggested above, by adding a Solidify modifier.  You should understand that this will double the number of faces/vertices in your model, however, so don't create an "inside" unless you really need one.  Also, before you upload, double check to be sure that all of your face normals are pointing the right way.  If they aren't, you will still have visible holes in your work.

[Rahkis Andel]

Agreed.

They said they were trying to walk inside of it, though, so it stands to reason that they can't get away with not having the additional faces.

[Codewarrior Congrejo]

As the others stated already, Secondlife uses Backface culling. This means that only the side of the polygon / face where the normal is paointing out from will be visisble. The backside of each polygon will be invisible to the renderer.

And only in case you really want to walk or be insides of this object (and didn't just have a camera look to see what it looks like from the inside) you will ahve to create the inner faces. 

You can do this by the solidify modifier, which Rahkis´suggested, or any other method to created the desired inner hull.

Be aware that you will need to re-uv-unwrap your model after you added more faces. And also make sure to calculate the normal's directions again to have all faces pointing in the right directions to be visible. (mesh > normals > recalculate outside)

In case the build is supposed to be walked in / through etc you possibly also might want to create a physics shape for it to define the walkable- and  the collision areas.

[Rahkis Andel]

Unless it's a ghooooost houuuse.

[Codewarrior Congrejo]

lol

[Erwin Solo]

I put some hollow mesh out on Da Boom for you to look at . 

http://maps.secondlife.com/secondlife/Da%20Boom/206/238/39

I just draw an inside.  Often I draw a simpler inside than the outside, so the number of faces doesn't double.  You can walk inside the pyramid by swimming under the edge via the small lake.  The pyramid has a much simpler inside than the outside.  So, the number of faces didn't double. 

For the geo-dome, I did let the number of faces double.  I just duplicated the geodome, scaled the duplicate down to about 95% and cut an access hole at the top. 

One does have to flip the face-normals to get this to work, as others have explained above.  Enjoy!