The fin is built up for accuracy. I use Profilli pro for my airfoil work. The airfoil is SD 8020 with the trailing edge thickened to a blunt 6mm and the root high point moved back to blend into the fuselage. The solidworks model helped to visualise the fit. Once the design was sorted out I printed out the ribs and used a glue stick to attach the printouts to the balsa. Lots of ribs for stiffness. Also made some leading edge templates for accuracy.