Measured for the edges to cut for the wing root doublers and wing walk.
I measured from the center of each rivet on the wing, to the side of the fuselage, and marked that dimension next to each rivet hole of the wing walk and root doublers.
Subtracted 3/16" for the gap needed to install the rubber wing root gap seal.
Drew lines to connect the dots.
Cut along the lines, then deburred and sanded the edges.