(Repost after accidental deletion)
Saxophone repairman Matt Stohrer of http://www.StohrerMusic.com shows a second example of how dents can be removed from a saxophone, this time via a process called «hollow tapping». This is not a method that is used super often, and the «dent machine» I reference in the video is this one: https://www.ferreestoolsinc.com/products/the-z60-dent-machine?variant=13454882564
This is not an instructional video, only an example so you can begin to understand roughly how the process works (when it goes well).
If you like this stuff, consider supporting me on Patreon: https://www.patreon.com/mattstohrer
Also check out the Open Source Saxophone Project: http://www.OpenSourceSaxophoneProject.com