I read in a mag recently..... use the lanyard plastic rope material that you would used when you where in the Cub or BoyScouts. It has a steamline shape, is very light and can be streached taunt. It comes in many colors including a metalic silver. I think you just glue the ends into a metal clevis.

I have used the round elastic string from a fabric store on a 1/6 scale Waco. I used a grey marker to color the white material. Loop the ends together with CA and then use fishing clips for the connections. It looks great, but is a real pain to assemble at the field.