The first steps to building the rudder is to fit the stiffners to the skin. You have to shorten, taper and trim individual stiffeners from the strips. Then you have to match drill the stiffners to the skin. You then have to debur the siffners and the skin. The rudder skin is extremely thin so you have to be very careful when you debur.
These are the 8 strips you have to fabricate 16 stiffners from