Cut and shaped the rudder base from .050 4130 steel. This part will have several features welded onto it. One of them is a flange all around. I used a piece of masking tape to get an idea hov what the shape needs to be of the flange. It turns out that what Dick has drawn on the plans is just about right.
Trimmed rudder base plate
Masking tape installed with proper flange angle
Flat pattern of tape shows that there is not much curvature except at very tip. Plans look correct.