Blender Icon theme for GIMP!
Launch GIMP and go to Edit > Preferences > Folders > Icon Themes and see where it looks for the icons, put the custom icon theme in that folder.
Alternatively, click the button "Add a new folder" and give it a new path to search for the custom icon theme(s). (needs restart)
Even on the default paths if there aren't one already! (Linux)
You can just manually create those and the index.theme file can be empty.
For v1. versions of this icon theme: (in 2.99 uncheck Use symbolic icons if available in Preferences -> Icon Theme*)
Color
Download
Symbolic
Download