Because your only solution (at least to you) is to use epoxy to keep using the only tanks you are willing to use.
It would not matter because no one knows how safe it is to use any epoxy on a vape tank.

Not even the manufacturers. At best they would give you their opinions, but that's not a safe way to go about this.
And even if you DID find a food and beverage forum where there MIGHT be some people who could MILDLY help you, they would either not answer you because you are a vaper or they would lambaste you for being a vaper.
What you are looking for is someone to come around and tell you what you want to hear, which is..
"Yeah, CountingCrows, [insert epoxy here] is not only effective to use on vape tanks, but it's 120% safe. I know, because I scientifically tested it and I am a certified epoxy expert who specializes in vape tank repair. So have at it, CountingCrows!"
But you ain't gonna get that.
You started 2 threads on the same exact topic because you are so desperate to find a solution that you figured maybe your approach on the first thread wasn't the best. But it wasn't your approach, it is your expectations that are out of whack.
You're desperate because your only options (in your mind) are likely to end in not having tanks to use, which is understandable. But you have GOT to be realistic!
Please understand, I'm not angry at you (but a little frustrated, admittedly), but you have to take a step back here and realize that you're not being very realistic. I've been there, too, looking for good, safe solutions. But sometimes there just isn't one.