Though there are arguably other benefits to this mod, there were only two reasons I wanted to put a cartridge on my carto: I didn't want juice getting into my mouth (through the drip tip I normally used, or the foam seals that come with cartos; neither stops e-liquid pop and spatter...) and I like to leave my e-cig in my mouth when I'm doing things so a whistle-tip cartridge is my favorite for that. So, for whomever may be interested, here it is. (This happens to be a Riva 901 with 808D-1 cartos and whistle tips all from Liberty Flights).
1. A simple whistle-tip cartidge. Half of the "D" shaped area (part that contacts carto) must be cut off to make a fit.
2. This is a "slice" taken from the rubber grip found on an ink pen. I use them for gaskets and seals; in this case, because it's a fairly loose fit with the cartridge going into the carto, I use it to slide over the joint after they are put together. It holds the two together while protecting against any leakage or rogue air flow.
3. The 808D-1 Boge LR Carto.
Notes:
Leave polyfill in if you want for extra storage capacity (theoretically, and practically as far as I can tell, e-liquid will not leak from polyfill in a cartridge down into the center portion of a carto unless you have grossly over-saturated the cartridge polyfill).
The cartridge is shaped like a capital "D" on the end; the actual hole that your vape comes through is just outside the flat edge of that "D," so, yes, it is exposed to the occasional gurgling/popping vape (this is relatively rare for most vapers; if you don't overfill, you shouldn't get a lot of popping juice jumping up through a drip tip and into your mouth). It would seem that this arrangement would not protect against getting juice in your mouth, but I suspect that the size of the hole (small) along with the angle of air flow (non-centered) as well as the air path through the cartridge does help to keep any liquid out of your mouth.
