my favorite graffiti movie is Style Wars, it's a bout the graff on the trains in New York in the 80's.
here's a tutorial i made
HOW TO MAKE A BINGO DABBER MOP
1. take the cover off and you'll see that theres a piece that comes out at the top.
2. pull it out.
3. on the inside of the nib piece there will be a plastic thing that helps control how much ink comes out, pull it out
4. fill it with what ever you want and put the nib back in or make your own nib if you want
^^but if you find a bingo dabber with those kind of nibs on that one don't use it cuz it will just rip off after like one tag
and something you should do is wear a respirater if your around a lot of spray paint fumes cuz if you keep breathing in the fumes a lot, after a while it can fuck you up