Please, please, people, unless you understand amps, resistance, and your battery's capacity, don't jump into mech mods.
We had a guy who came every month to exterminate our home (we live in the south and I can't stand those freaking huge flying roaches!). He was trying to quit smoking, so I suggested he try vaping. One month later, he came to service our home, and was so proud to show me that he was vaping!
To my horror, he had a set up that a "friend" did for him. It was a mech mod with a drip topper, and a coil the "friend" built. He had no idea what ohms it was, what kind of battery was in it, nor what nic level of juice he had. I had some extra eliquid I gave him to try different flavors - it was an appropriate nic level for someone who recently quit a pack a day - I think 12 mgs. He made a big show out of changing the cotton for a new flavor that this "friend" showed him. But he had no idea how to do it. He was trying to shove a wad of cotton through a coil. OMG. I showed him how to twist, taper, and snip the cotton to thread it through the coil.
He took a hit off of it with the sweet tarts flavor I had, and was light headed for several minutes. Right then, I knew his coil was sub ohm.
Mech mods and sub ohms are not for novices that have no idea what they're doing!
I told him to put that crap away before he killed himself. I dug an old Vamo out of the cabinet, a Kanger Protank 2, some spare coils, a bunch of 12-18 mg of eliquid flavors that I had moved on from, and 2 older low amp batteries that were safe for the Vamo. Plus, a battery case for them with the warning about loose batteries and the fire hazard.
I did my best to try explain coil resistance, amps, battery load, and the difference between mech mods and regulated box mods. But it was like trying to teach Latin to my dog.
I saw him the next month and he was happily vaping away on that FastTech Vamo II. He left the company after that, and I never saw him again.
I hope he didn't go back to smoking. But in any event, I did my best to stop him from blowing himself up with that contraption. His friend probably meant well, but that's how people end up in the news with an exploding ecigarette.