Lexan is strong, but it's soft. For bullet-proofing, you want materials that will absorb kinetic energy and disperse it. Anyways, most cabs had glass. But by the 90s, particularly fighter games, they often didn't. Candys generally don't, either. They both have bezels over bare monitor. As for distance, recall that DK's bezel/plexi combot is at least 60 degrees from it's monitor. Most bezels of golden age games are about a couple inches distance from the screen.