Human beings are wired to do drugs, all throughout history we have sought ways to get high. On the face of it, nicotine itself isn't any worse than caffeine (aside from the vasoconstriction) - both are highly addictive, but alone without any other substances aiding in the addiction it is relatively easy to quit.
It really amuses me that as a society we are finally starting to end the war on drugs (slowly, but surely) yet because of the public opinion on cigarettes ANY alternative delivery system for nicotine is stigmatized. I don't smell after I've been around people that vape, and many people I've been around that quit smoking through e-cigs are substantially healthier than before - I think that alone is enough reason to incentivize these products.
You aren't going to stop people from seeking pleasure, trying to "save the children" is almost universally nothing more than FUD to try to pass a political agenda. Are people going to pick up vaping without ever smoking a cigarette in the first place? Sure. But there was nothing stopping them from picking the worse alternative either, and I would much rather they don't. For all the talk the FDA makes about this being in the interest of protecting public health, I think it's going to do a lot more damage than good.
Lastly, this is only going to hurt small businesses who have started a multi-billion dollar industry. Modern vaping hardware evolved from hand-made devices built from flashlights, a frightening time in the history of the community where ohms law was something anyone who wanted a satisfying experience was familiar with. Modern devices have substantially better safety features, and all of that is going to go away to satisfy the public perception. I hope the FDA is proud of themselves, they have condemned tens of thousands of people to death.
I mean... lol
This isn't a single-faceted issue we are discussing here.
The past year has seen an explosion of temperature controlled devices, but they require coils made out of specific metals (Ni-200 or stainless steel). Ni-200 is almost unilaterally a bad choice, one of those getting too hot releases noxious chemicals - so if the control chip in the device malfunctions (there have been reports of this) it is possible to have health repercussions. Stainless steel has been a good choice, overheating will just burn the cotton wicking - not good for you but compared to breathing air in urban centers for years it's not going to make a dent in your overall health.
I take it you don't eat grilled stuff?
I stopped thinking about mixing my own when I discovered Poundland carries branded eliquids. £1 for what seems to have a widely standard price of £3.33 or £4 in the vape shops and sites.
In the UK glycerine is available in pharmacists for ~$2 per 200ml. https://www.boots.com/en/Value-Health-Glycerin-B-P-200ml_852...
The devices themselves can be bought from overseas - AliExpress has many variants, some for <$10.
At that stage, the 'safety of e-cigarettes' is equivalent to the safety of inhaling atomized glycerine. Stage smoke.
Flavourings - you can look for things which are used in aromatherapy (e.g. menthol crystals), but you'll probably want to study whether any chemical changes can occur under heating.
Pre-mixed nicotine is a difficult one. I don't use it so I'm not sure if you can acquire it from trustworthy sources.
I would not want to fall into the habit of using e-cigarettes produced by tobacco companies such as the 'vype' disposable (British American Tobacco). They have a history of producing methods to increase the addictive potential of cigarettes, ramping up nicotine levels, to cheating on tests, using ammonia to produce 'freebase' nicotine, etcetera. I wouldn't be surprised if the same bag of tricks comes out in the e-cigarette market.