I have heard of this being done as well but personally I'll stick with my RDA and RBA for rebuilds. I would "assume" to rebuild it you would want to test it to see how many ohms it is then you have a number so you can match that when you wrap your coil. You would look at how it's wrapped and copy that then test the coil when you are finished to make sure it's the desirable ohms and safe before you use it. You can use a ohm tester to do this. They have easy ohm testers that are 510 threaded where you can put the coil on and test it that way. That's how I would assume it would be done. But I've never personally rebuilt one. But I do build coils for my RDA and RBA. I usually just buy the replacement coils for the other types. I hope this helps a little.to make it correctly I would say You would want to make sure you had the same gauge wire and wick as they used in the original build. Best wishes.