Well, right now it's just 1/4" birch plywood over 1/2" MDF, however the 1/4" plywood will be used as the template to machine the 1/4" plexi to take it's place.
Would work fine to sandwich graphics under it as mentioned above, but I'm going to frost the entire panel (sand blast) so that when I edge light it, the entier thing glows. Usually you can do this with LED's fairly easily, but I think I'm going to run a slot around the outside edges and sink EL Wire in there to try and get a very uniform lighting pattern. I've done this often enough in my custom car audio installs, so I'm just transfering that knowledge to my cabinet in hopes of something a little unique

May be a while before I get to acutally doing it though. Still trying to finish off the rest of the cab first.