the tool that i used to put the dents in was a drumel i first started out with bigger type grinding wheel and then i switched to the wire brush peace, it seemed to be more maintainable in the fact that it did not remove the material so quickly. I anyone else is to do that the brush is the way to go but you gave to rotate the armor piece so you don't end up with brush strokes all in one direction, then you take a finer grain sand paper to the dent to smooth the rest of it out good luck to all the other fetts out there.
P.S. If anyone like my armor enough i may sell a set just like it un-battle damage or battle damaged, the battle damaged will cost a little more due to the labor of puting in all the dents and dings. thanks again.