For a mechanical mod and 20amp minimum
batteries, 5wraps of 24ga @ 3mm, dual
coils, pulled all the way out to the air holes (long legs) is gonna be close to .3 ohm. If you have 30amp
batteries, you can go down to 4 wraps which puts you closer to .2ohm.
If you have a variable wattage device, id use the 24ga at 6-8 wraps and vape it between 40 and 75 watts, however you like it.
You did leave out an important piece of the equation, what device will you be using?