any suggestion as what to use for wing wires on my Eindecker

If your wire rigging is just for looks make it out of black elastic thread. I did the flying wires on my Elder 40 using the elastic thread and it makes for very easy set up at the field and gives the look. I have also used the elastic thread for fax tail wires on many of my smaller (1/5th scale and smaller) Piper Cubs. However, if the wires are functional, elastic thread isn't going to help!

A lot depends on how you want to fly your Eindecker. If you expect to do even mild aerobatics you need functional wires both top and bottom. Something of this nature http://shop.balsausa.com/category_s/141.htm
If you are going to just fly circles, do touch and goes, etc. then most any other type of material can simulate the wires. I used black fishing line. That was fine for about the first 20 flights with mild aerobatics. After that the wing started flexing and i had to stop. The plan is to add functional wires before spring.

halflight started a thread, http://www.rcuniverse.com/forum/kit-...eindecker.html. Doesn't say whether the 40 or 90. Aren't those standard semi-scale sport planes where wing wire bracing would only have to be cosmetic and not structural?