@dklgood thank you so much for that video 
That helped me understand things better. I was looking at the person who made the jig for the square shotglasses up here and created the multilayered jig for the shot glasses and I remember thinking it was a good set up to fit all the glasses in there so you can run an engrave multiple times … but I was not clear how once you made that set up how you could be absolutely sure that the first run of engraving would be perfectly centered on each glass… I was just having a hard time wrapping my mind around it but now I realize he cut those spots and kept the jig in place - did not move it or had it clearly marked to put it back in the exact spot.