I found:
- https://wiki.faforever.com/index.php?title=Advanced_Strategic_Icons
- https://forums.faforever.com/viewtopic.php?t=2740 (404)
- https://direct.faforever.com/2014/07/advanced-strategic-icons/ (??)
and this repository from @BlackYps to automate tasks in Gimp.
Search functionality is broken on the old forums. How do you convert the link to the cached forums?