If you build octagon panels at your studio then you probably know the difficulty in laying out the eight sided figure properly.
Most people end up doing the pattern by trial and error.
Here is a free tutorial that explains how to measure the octagon sash at the job site and how to accurately and quickly lay out the pattern. It may be helpful to those who have had problems with these shapes. There are methods for the layout of unusual design shapes available in many woodworking books, your school math books and the local library is loaded with them. It's good to learn and your library is an outstanding source. Most people end up doing the pattern by trial and error.