Short: CLI command (OS2.0 or later) that makes icons.

MakeIcon is a CLI command for AmiagaOS V37 and later. With it you can
create icons for any file, directory or disk. It's better than simple
coping an icon file as:
   - you can use the dafaults icons.
   - several icons through patterns.
   - new icons will be displayed immediately (if possible) on Workbech.
   - you don't need to type so much.