Not sure if the TF2Items API is needed for this, but this seems like the appropriate section, so forgive me...
How can I add a charge meter to a player, so as to track when an ability is ready for use?
In my case, I am working on a blink ability. I can easily have a variable that counts up the percent charge over time, but having no charge meter on the gui, is confusing. The gui is where I am stuck.