Thank you for you answer!
Thats exactly wat i want to do.
I will explain you my small problem: wend i send my model in sketchfab, i need to parameter all the surfaces.
If i want to show the same object with some changes of color of somme parts for exemple, if i make copy and past of the first model i have just to change the color of somme parts of my second object .
Thats verry simple and faster...
I hope you have understood my need, because my english is verry bad!
An other question: cans we speek french here?