an option would be to put the cup in a silicone sleeve like I mentioned a long time ago, the inner cap being its lid [make the sleeve just simply a bigger silicone cup that holds the ceramic cup inside of it]..[or a metal, permanently fitted ring holding the ceramic in place (metal similar to the threaded connector end)]
Or B) instead of the black rubber sleeve, make a straw as long as the inside of the carto, made out of Lipton pyramid/filler material, which lines the carto's interior and works as a wick (remove the wicks, except inside the cup), as I mentioned not long ago.
The more modular and easier to disassemble, clean, and re-use, the better the carto is,
and the cleaner and better it can be kept.
[no need for bacterial claims, during a fear factor about the gunk]
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Also it depends on what kind of solvents people vape.
Don't some ejuices even have a small amount of alcohol in them? And another question: does alcohol itself even mix well with filler material and wires and silicone?
I think Scott or someone once mentioned something like atomic cyanide or something like that did not mix well with the caps or something about the cartos... and quick1 or someone may have mentioned something about alcohol and silicon, tho I thought he meant silicone, and I'm not sure if it's all alcohols or not..