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I saw this someplace but can't remember the trick.

If you want to say, center a piece of trim above a window, and the trim has deliberate overhang on each side, so you want that overhang to be equal on both sides. Is there a "trick" for centering this besides eyeballing and besides measuring with a tape? Somehow using the board itself and lining it up flush with the end and making it or something.

Sorry if it's vague, I though it was on a Larry haugn video but idk.

Thank you