Vertical stab parts are put together, minus the skin. I’m putting in an optional antenna for VOR/Localizer/Glideslope reception, so I had to make a doubler plate for the top spar where the antenna will be mounted to. To make the plate, I used a sheet of 0.032″ 3003 aluminum that I bought from Amazon a while ago, and simply traced the pattern from the rib.
I added wires and grommets for the antenna and for a light that will go on the top of the rudder. Since I had to pass the wire through two of the lightening holes, I attached some nylon caterpillar grommet material to the edge and secured it with silicone sealant.