Adding an "internal" texture

[SirDanest]

A lot of meshes in the CK have only a texture on the outside, or the inside, and are all but invisible from the other direction.. like an exterior building piece would be invisible if you somehow were within it.
Do I need an external tool or an entirely custom made new mesh if for instance I want to add an internet texture to a piece with only textures on the outside?

[Ethreon]

The quickest solution is to make the texture double faced. A more tedious one is to fix the mesh to have two faces, which in the case of architecture would be required.

[Zoroastre]

In blender that's the solidify modifier, IF I remember correctly. That's quite doable in smim like project, you only need time and tedious resistance..