Thickness?

 From:  Frenchy Pilou (PILOU)
7252.1 
How to give a thickness to this surface ? (Shell)
Even you take one triangular surface that don't work!


http://moiscript.weebly.com/uploads/3/9/3/8/3938813/thickness.zip file 3dm

EDITED: 12 Feb 2015 by PILOU