I finish your tut and have an idea for that method, but a can do the ilustrator paht render correctly on invig, maybe this is no the right forum... but how do you made only one ilustrator path render on ivig? couse i try to make a resistor shape and the render seems like a plate. Sorry if I dont explain well.
You can make a resistsor shape by using two Illustrator circles. One representing the diameter of the resistor and a smaller one representing the wire that passes through it. You the adjust the z depth of each object and change the bevel to something small. That should do it.