Hmmm...I didn't consider the tube - but if one had no access to replacement cartos, I wonder if something could be made. I realize building an atty would be easier, but I've got this Professor from Gilligan's Island thing going on in my head. I think modding a coconut would be fun.
I know of one person, LGD, he was a mod here, he mcguyvered his cartos for dripping. But that's pretty much all you can do with them. Let me see if I can find that link, hang on.