Below is a duct protruding from a cone. in order to get an overlapping layup, I'd like to trim away the cone, leaving 1 inch or so of the surface offset from the light blue line (continuing all around the duct). I've tried a lot of things to approximate this (none have been successful), but haven't even thought of anything that would do it exactly. What I really want is to extend the cone surface negative 1 inch.

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