Thank you PapaSloth
Seems to require less wraps the larger diameter you use but i guess you have to have the atomiser to see how much space you have to work with. As Im wondering how many wraps and size of diameter can you have.
Yes, that's exactly right. The longer the hose is, the less water will flow through it. If you take a 100 foot hose and wind it into a 2 foot coil, you get 50 wraps, but if you take the same 100 foot hose and wind it into a 1 foot coil, you get 100 wraps. It's the same length of hose though, so the same amount of water will flow through it, regardless of whether it's 100 1 foot wraps or 50 2 foot wraps.
You're also right that the limit is how big your build chamber is. A bigger chamber gives you more room for bigger diameter coils and also for longer coils with more wraps. Remember, you also have to fill the coil with wick, and make the wick pick up the juice, and a bigger coil will require a bigger wick. So, that can be a limit as well.
Punching above my weight atm but just getting a feel for it.
As long as you measure your builds on an Ohm meter before firing them on a battery, you really can't go wrong. At worst, you might miss the target you're shooting for, and have to adjust your build or start over from scratch.
Always use an Ohm meter though, and recheck your build every time you screw on a chimney part, because you might have gotten a short. I had a short once after screwing on my chimney, and the wire actually arced and welded itself to the chimney when I fired it. Oops. Don't do that

I could have seriously damaged my battery if the wire hadn't burned out.
Oh so more wraps can be ok due to spreading the same amount of heat over a larger area. I see people just doing 4-5 wraps and i get it that they are going for 0.5 or less and I'm not thinking of copying them but these videos make up most of the tutorials online.
Yes, you mainly see cloud chasers working on dual coil builds, but that doesn't mean they can't be useful for those of us who just like a little more flavor

I'm not a cloud chaser, but I do like a denser vape, and building dual coils has helped me to produce more vapor without getting burnt juice.
So two wires where one end of each wire goes to its own negative but the same positive is parallel ? For atomisers I have seen with one positive post and two negative.
Yes, that's exactly right. Both coils have their own negative posts, but share a common positive post is still a parallel build, and will have half the resistance of each coil total, and push twice as many amps as with one coil. Or, if you had three coils, you'd have 1/3rd the resistance, and push three times as many amps. Once again, it's like hoses. If you attach two hoses to the same faucet, you get twice as much water coming out, and if you attach three hoses, you get three times as much water.