This small gadget holds a paint pen and has a groove for an 18 gauge wire. A small hole in the middle of the groove allows the paint pen to leave a trace on the wire. The original idea came from Tom on the Carpokes forum. I created my own version to better suit the wire gauges of my projects.

18-AWG Philmore 78-21810 series wire is the exact type being used. A Sharpie brand oil based paint pen with a fine tip is the exact pen.