I have a model that I hollowed out and now want to give it an open top. I would like to just have Blender create a face like shown in the picture, but instead it fills the whole thing with a face. How can I change this?
Side view of image https://i.stack.imgur.com/KN0Ry.png
Top View (red is what I want to be filled in): https://i.stack.imgur.com/uSWzq.png
What happens when I fill in a face https://i.stack.imgur.com/3EPvd.png
Thanks!