The lower part of the rudder spar contains several parts which comprise the control horn attachments, and there is a fair amount of work necessary to complete the assembly.
One task is to open out a hole in the rib web to 3/8", to align with the existing hole in the spar through which one of the three rudder attachments passes. As the photo shows, there is very little room for error here.
The rudder control horn attaches to that web, and requires a shim to be fabricyed from 32 thou Alclad material from dimensions given on the plans - this is the first truly "from scratch" part that the plans ask you to manufacture - I'm guessing that it won't be the last.
