So i am making this curved washer that will be made from flat rubber material. If you flatten what i have in the picture the edges are not perpendicular to the top face. I drew some lines to make it more clear. I tried this in sheet metal (which is where i would get the flat pattern) but i couldn't get it to work to be able to show what i needed help with, so its just using normal features. Just to clarify, the very top middle 4 lines, line up with the faces but the back and front 4 lines do not, on the inside i need it filled in and on the outside i need it cut away.