TIL: You can export Icon Composer .icon files from the cli tool
Icon Composer ships with ictool — buried inside the bundle:

/Applications/Icon https://Composer.app/Contents/Executables/ictool

Export any appearance at any size

ictool MyApp.icon --export-image --output-file icon.png \
--platform macOS --rendition Default \
--width 1024 --height 1024 --scale 1

The --rendition flag lets you export all 6 icon appearances individually

Great for automating web assets, favicons, and press kits from a single .icon source file — no manual exports needed.

Thanks to @johnbrayton for documenting ictool:
https://virtualsanity.com/202507/icon-composer-notes/

Icon Composer Notes

I talk about working with Icon Composer and the changes to icons for Apple’s OS 26 releases.

@leogdion @johnbrayton This is fantastic. In 15 minutes I vibe coded an app that now extracts all the images I need for my YouTube Videos and resesources for my project launch screens
@StewartLynch @johnbrayton Nice! here's some of the script I used for my app if you find it helpful:
https://gist.github.com/leogdion/f9330d9f624c6b623306648bfe23c8f5
Export Icon Composer Icons for Press Kits and Web Sites

Export Icon Composer Icons for Press Kits and Web Sites - generate-icons.sh

Gist