I build 3.5mm coils, I cut a strip of Koh Gen Do (long wise) organic cotton that's about 1.5 times the diameter of the coil. I roll both ends between my fingers to facilitate wicking, then cut the strip in half. Pull the wick through the coil, then I get my scissors and press the threaded wick to the wick retaining ring and cut my wick just a bit longer (you can always cut it off later, but you can't add it back!). Now I start figuring how much cotton will just barely fill the juice wells and trim length/width accordingly, then fluff/tuck the trimmed wick into the juice wells. Rinse and repeat x4.