Granted I only own three pieces of plexi at the moment, but of the two marquees that I have, one is 1/8 and the other is even thinner. I have a piece of 1/4 inch for sitting in front of the monitor. A couple of the other cabs I looked at were pretty much the same. The thing with keeping the marquee thinner is that it makes it easier to pop out when/if the need arises in my opinion. In the arcades the plexi in front of the monitor was a bit more to protect the monitor, whereas the plexi for the marquee is just for show for the most part, so it's really up to you. If it would be cheaper to have someone cut everything from a 1/4 inch piece then go for it.