die grinder... or drum sander in a drill? just make a circle a bit bigger than you need in a piece of aluminum, then use a fine sharpie to draw the circle on your wall and grind out to the line, it doesn't have to be perfect, the flange will cover it.
-blizz
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2001 GMC 6500 Topkick, 22' box, dropped frame, designed to fit into a 9' garage door. 3126 CAT 6spd Man Lo-Pro 19.5's w/ 3.07 rear axle ratio
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