https://github.com/jilavsky/SAXS_IgorCode/tree/master/User%20form%20factors%20for%20Irena is location where I can add form factor functions for use in "User Form Factor" option in Modeling package (tool) in Irena. If you have any form factors to contribute, please send them to ilavsky@aps.anl.gov. You may be able to help other users.