I don't think I've seen this posted anywhere, but since it's so simple so I thought I'd pass it along. 
I find the four hole batteries can sometimes be a little too airy, so I bought some small rubber bands and I twist them around where the battery and carto meet.
Then I found a container in the toddler section in WalMart that had little divided compartments with a different color in section, so I can also use them to identify flavors, too. I think there's 250 of them all together for around $2.00.
These are different than regular rubber bands because they're really narrow and are more thin and flat than rubber bands, so they almost look like they're a part of the ecig. Think cassette tape (like when your cassette player tried to eat your tape and you stuck a pencil in the hole to try and wind it back inside)except really narrow and stretchy.
I like it better than trying to plug the holes because, depending on the carto and juice I'm using, I can adjust it so it covers less and sometimes none at all.
I use a metal drip tip on my cartos and have found a few of these wound around the top give it a softer feel, too.
I find the four hole batteries can sometimes be a little too airy, so I bought some small rubber bands and I twist them around where the battery and carto meet.
Then I found a container in the toddler section in WalMart that had little divided compartments with a different color in section, so I can also use them to identify flavors, too. I think there's 250 of them all together for around $2.00.
These are different than regular rubber bands because they're really narrow and are more thin and flat than rubber bands, so they almost look like they're a part of the ecig. Think cassette tape (like when your cassette player tried to eat your tape and you stuck a pencil in the hole to try and wind it back inside)except really narrow and stretchy.
I like it better than trying to plug the holes because, depending on the carto and juice I'm using, I can adjust it so it covers less and sometimes none at all.
I use a metal drip tip on my cartos and have found a few of these wound around the top give it a softer feel, too.