Ysvry: Sorry, it was a mistake. I was thinking in tests made when modelling penguin, and that was not a good one. A selection of vertex or faces can be duplicated but not instanced. o-q: That is the setup to modelling with sub-d. That is not needed in maya, in old versions of max was needed a similar setup,... It seems there are too many steps, but they are easy and quick to do. The important thing is mantainning middle vertex in the same plane.