How do i make a inset with rounded shape? i was thinking about trying to make a model of the bottle in the picture i attach. I have right now just added a block and used the knife tool to select the area in question.
I think i can handle to form the shape of the bottle, but the selected area is kind of a inset but rounded into the shape of the bottle. So my question is how to do this. I tried with the knife tool but the result was not very good, i allso had a idea of using the boolean tool, but i guess its not more easy to create that shape as a stand alone object.

I would be very glad if some one knows a good way to fix it.
Sure you can sculpt it, but you can also just mesh model it...



The edge requires a loop that you can bevel depending on how sharp you want the edge. The challenge is smoothing out the geometry at the pinch...



Also just added a mirror modifier and of course the sub-division...