ORIGINAL: FlaBob
The ''wing supports'' are the dihedral braces. I remember from my Superstar that I put together years ago that they were two of the plywood pieces that had to be glued and then went in each wing half to hold the wings together.
Welcome to the RCU forums, Bob.
All good advice above.
The manual specifies to sandwich-glue the two supplied 1/8" plywood braces.
Since you are making your own, I believe that you can make one piece from 1/4" plywood.
The attached schematic explains how you can measure the exact angle for the brace.
1) Put the two half-wings together with some tape on the bottom of the central joint (no gap).
2) Place the wing upside down and overhang one half-wing from an elevated surface.
3) Measure as indicated.
4) Calculate the offset of the end of the brace using the formula.
5) Make each half of the brace a littl eshorter than each wing pocket.
6) Try obtaining a tight and nice fit between the wing pockets and the new brace.
Best luck with your project!