One of the ingenious "gadgets" I discovered recently. It's called Comb-A-Color Quick Haircolor Applicator and I got it off Drugstore.com in one of my hauls for $4.99.
It's a plastic squeezable tube wherein you put your home hair color kits into the bottle after preparing, close the comb cap then apply to hair.
Angle it 90 degrees to avoid dripping but flow can be controlled. The dye comes out through the holes of the comb when you squeeze the tube so it's so easy to apply the hair color. I actually had fun doing my hair for the first time. It's also easy to clean as you just use soap and rinse it.