I love the Kanger sub tank coils for rebuilding. Vertical or horizontal. If you decide to go vertical, you might try this. Wrap your coil, then carefully bend one leg up, and the other down. Keep it on the thing you used to wrap the coil. Then wrap a piece of tape just bellow the coil and tape the leg down. this keeps the coil in place while wrapping the OCC. cut the OCC to the width of your coil plus 1 mm for the top, and one for the bottom if you can. With a bit of practice you will be able to roll the OCC around the coil like you would if you were rolling a roll your own smoke. Once you have the coild wrapped in cotton, and you have tested to see if it will slide in the coil body from the top with just a tiny bit of resistance, then bend the top leg over you cotton warped coil. who cares if it is touching the walls of the coil body, as this is gonna be the ground . Gently with a twisting motion insert the coil into the body until the bottom of the cotton touches the bottom of the body. Make sure the leg that was on the outside of the wrap is bent over the bottom of the coil body, then insert the rubber grommet or gasket with the other leg through it. Bend that over the rubber gasket and insert the positive pin and trim them both as close to he unit as you can get.....I like to adjust the coil for center and clean up any loose cotton by inserting the tool i wrapped the coil with through the coil after it is finished and adjust as needed....supper easy once you do it a few times. Things I have found....if you do micro coils, you can not work out hot legs and the rubber gasket tastes really bad...if this is an issue, and it will be more than you would like...then build a wire welder and use nickel wire for your legs..This gives you better control over the ohms and prevents any hot legs from making you vape rubber!! also like to use nichrome wire as the ohms are lower so i need less wraps to get the desired resistance....Hope this helps in some small way. If you want to make a wire welder i can give you the super easy diagram and parts list that I used...It is super easy to make, and welds 22 gauge wire or 32 gauge wire every time.....Enjoy!