Hi,
How do I edit a surface to make it look concave?
I want to achieve the effect of sunken material compared to artificial reinforcements.
It’s about the marked surface
I want to achieve an effect like this or similar
I can modify the surface, but it always ends up distorting the edges; the edges have to stay in place.
I’d actually have to stretch the surface, but how?
I found a solution that solves my problem 
well it converts the surface into a patch when you change the position of the hole like this. it is usable but be aware that the mechanism to reshape the surface is not bulletproof, if you change the shape once more it might lead to extreme and random distortion depending on the geometry. you can achieve the same by placing a dot or the same circle at the elevation point and use the egdes of the lower surface to create a patch with option tangency, with history enabled you can then move the point or circle around endlessly and in real time till it has the shape you would like to achieve.
