I have a mesh where the faces should connect at the center in a single vertex, but the top is cut off at the moment (like a pyramid without its top). I want to add this top now, but I don't know how to correctly align it. Here is an illustration of what I want to achieve:
And a second question: How would I know resize this pyramid-like shape? I mean, the base should stay the size it is, but the rest should go higher or lower. It is obviously easy if every side of the pyramid is only a single face, but since my sides contain multiple faces, I don't know how to preserve the angles. Again an image, since I'm really bad at describing.