For those people who don't have MOTA. There are other ways to produce the layouts for your cones. Here is a Zip file that contains  a very good write-up that should help you remember your  High School  geometry lessons.
Many Thanks to MARK VENETTOZZI for this excellent article.

PIPE ZIP

So here are the flat sheet metal blanks that I cut out after transferring the patterns on to the sheet metal. They cleaned up alright with a file and some emery cloth. You will notice that one of the cones is made up from 8 pieces and the other one is made from 3 pieces. That is because I have used MOTA to help me bend the header cones. You can read about Bending Cones here…..