@stephomi I think an improvement for the extract function could be an option checkbox to do a double extraction, with the same thickness going in both directions. That is, if I request 30, it should make it 60, 30 towards the normal and the other 30 contrary to the normal and left the new element at middle. This way, the new piece would fit perfectly over the masked surface. Not sure if I’m explaining myself clearly 
As of now, it always ends up separated if you smooth the extract. Then you have to assign more thickness than necessary and then push it into the surface. But if you extract several masks at the same time, you have to reduce all of them at once, and by reducing proportionally they become smaller than the original mask was.
It’s already there in 1.77, by choosing the extraction sign ±.
1 Like
Genial 
thanks