A bicycle gooseneck is wedged into the forks by tightening the bolt on top of it. Inside the forks, a wedge is being drawn uphill over the angled bottom of the stem by the draw bolt.
The Baker tool mimicks the wedging of the bicycle gooseneck.
The wedge is touching the bump inside of the shotgun barrell tangentially. Plannishing relieves the stress in the bump of the barrell, allowing the pressure from the wedge to push it out incrementally. When the wedge becomes loose, or the tightening handle can be turned a little more, then the plannishing can reoccur. Rinse and repeat.
When the dent has been fully raised, and the stresses around it relieved through the hammering, the wedge can be removed by:
1. loosen the tightening bolt,
2. A sharp wrap on the tightening bolt head will drive the wedge down out of the taper, and the whole assembly will slide out of the barrell.
This removal process is exactly how one removes the handlebars from the fork of a bicycle.
I suggested going to the local skill center, because young people need to learn, the tool is very simple, and it gives the youngsters a look into the future application of their training. It would help them tie what they are learning today, with what the real world can do with such training.
