I have uploaded the icons I used in the ADL Workbench into the reference-models Git repo. They can be found for the various reference models at locations like this.
The icons are a mixture of icons originally used in CKM, and some (rougher) developed by me for AWB. This resource might be a useful starting point for people wanting to try and make a nicer set, or simply reuse them as they are (e.g. you can obtain a .zip of a directory containing icons from any Git repo very easily).
- thomas