Ok I hope I can describe what I am trying to do.
I have a AR15 lower and have a buddy who would like for me to make him a drill jig. So I have am AR15 model in Fusion. How could I get the side profile geometry projected off to a new plane so I could mill a drill jig.
I also need to project the fire control group geometry.
Why don’t you create a new component (milling jig), join them with an negative offset then use the combine tool with the keep tool function checked? It is how you create soft jaws.
Youtube search for “soft jaws fusion 360” nyccnc has a great tutorial.