by Davo Smith.
There's no facility in Moodle for custom stamps per-user or per-course.
Obviously, you're not limited to just using stamps - there are a range of other annotation tools, including typed comments, but if you need specific image stamps then they are defined at the system level.
In theory, it probably wouldn't be a massive amount of code change needed to add an extra set of stamps that could be either per-user or per-course (or per-activity), or some combination of the above. It would however need a developer to spend a bit of time to implement it (either for free, if you could find someone, or as a paid job).