Thanks. Well, AQ's site recommends a cutout of 11.1875" (11 3/16") so I just went with about 11 1/2", it's not the full 12 and should hold the speaker fine. The puzzle pieces are a bit more of a pain in the ass, although I did just do it with a jigsaw & not a table saw like I should have but hey, make do with what you got on hand, and it came out half decent.
Screws are in already, putting pics up now. Probably going to remove them & use liquid nails or something then rescrew & sand. Dunno what I'm going to coat it with, carpet or paint...I'm leaning towards a carpet readily available because I'm going to get a batt & make a false floor/side wall assembly perhaps...It's all in the plans.