For the rigging on my FK.8 I used 0.1mm monofilament or the same size invisible thread would do the same job. The brass tubes I used are 0.4mm which has a 0.22mm hole (Griffon Models Tube), this allows two runs of the mono through the tube, very thin or runny CA (super Glue) holds it all together. The monofilament will add a great deal of strength to the wing assembly while the elastic thread adds only minimal rigidity.
Des.