Sully is one of my recent heroes. Aside from being generally awesome, he puts out a ton of videos on guitar building and repair. I honestly wish he lived down the street from me so I could wander down to his garage a few times a week.
Here’s a video of him demoing a new fret leveler (the Katana) which works with the strings still on (whoa). Anyway, I’ll let the master show you more about it while I go order one for myself.