I am terrible at building coils. For RDA's I've been buying coils from fast tech. They work pretty good but are a bit flimsy due to the thin wire, but they work. I've been trying some of the vendors on ebay and some of them do terrific work. I did order a jig to try and make my own but odds aren't in my favor. With the fast tech coils it is so easy to screw them in and pull a strip of cotton pad thru. I know some will look down on this but for those of us with trembly hands its good to have options.