We cut the wiring channels into the foam after the top of the wing has been bagged and is ready. In our earlier builds we cut it out by hand, inserted the wires and closed the top with a strip of depron foam. While this worked quite well, the wires always got in the way of the building process and sometimes the channel would be visible in the abachi after closing up the underside of the wing. On occasion we would also have some epoxy entering the channel during the building as a result of which the wires were glued stuck.
With the Urupema we tried out a new way, which is much easier. Richie, the team member who builds our plugs, and who came up with this idea, designed two nifty add-ons for a low-wattage (15-25w) soldering rod. Usually our planes are 3 Servos per wing. He thus designed one add-on for a single wire (aileron servo), and one for 2-3 wires (all three servo wires). Being a goldsmith by profession he made the add-ons from silver, which is also resistent to high heat and a good heat conductor. Just guide the soldering rod with the add-on along a steel or aluminium ruler and you have your wiring channel. Once the wing is finished and the servo openings cut out you can easily pull the wiring through the channels.