Even using the same materials, there's always a chance of inadvertently changing something or shorting the coil on itself/the metal part of the head. Trust me, I've done that, and thought I knew well enough..didn't have my meter handy cause we were moving, dropped it on an Ego, fired, entire bottom of the Evod I was using lit up orange and the battery failed instantly. Well, probably the control circuitry failed, as it didn't explode, but still.. Always have a multimeter, or a mod with an ohm reader if you're going to do rebuilds. You'll save yourself money and potential injury in the long run.