If you need to run servo wires in a wing without the string leading the way here is a trick. Cut off a single flute of coroplast, trim it very clean. Run a long piece of soft copper grounding wire in the flute, leaving about an inch of the coro hanging off the front. Bend it in to feed thru the first and if possible the second rib, then slide the coro off the wire thru the ribs. Once you have the coro reaching the exit hole feed a piece of fishing line back down thru the coro. After the line is thru, carefully pull the coro out with the fishing line remaining. The coro wont cut your covering as easily as a piece of wire and also tracks itself better than using the weight on a string method.

Happy builds!