The trick is finding a carto/clearomizer that can handle the liquid. Most tinctures I've found at dispensaries have some alcohol in them, which I wasn't cool with, so I started trying to make my own, with some success.
I purchase a pg/vg blend, usually 35/65 respectively, and simply melt BHO into it, while it's in a warm water bath. When it gets warm enough, I cap it, and shake the living hell out of it to get it to mix well. I'll repeat a couple times (warm then shake) until it seems like a good solution has formed.
Then I'll let it sit for about 24 hours. In my case, I can tell if I need to increase or decrease (dilute) the solution based on how much of the extrace has come out of the solution and created a ring where the meniscus (top level of the solution) has been resting during the 24 hour resting period. This waiting period I prefer to let happen in a low-light or dark place, in my case a drawer, as I've heard it helps a bit (no confirmation on that though).
The BHO does naturally come out of solution at first, but repeated shaking, and allowing it to "steep" to some degree, help with the process in the long term.
I personally prefer Gentleman's brand tincture tanks, as they have a few more holes and burn the solution/juice well when given 4.2v. I've encountered zero build up or leakage. The only drawback I've found is that I can't quite dial up the potency to the point where I can take 3-5 hits and get medicated. At present, I have to kind of sit with it and take 10+ before feeling the medicine kick in.
Notes/comments/suggestions are always appreciated, but just wanted to share.