Mehndi MadnessTM Blog
There are many choices of applicators. The most common for professionals are cones and squeeze bottles.
Squeeze bottles are popular because you can get nice looking designs without a lot of practice. And so, if you don't want to spend a ton of time perfecting designs while mastering an applicator, the squeeze bottle might be right for you. Most professionals complain about their hand hurting after a short time and thus have difficulties getting through a long event. The bottles also suck in air as you use henna. This means that as you empty the bottle you have to push out all the air before henna will come out. So keeping the bottles full is helpful.
Cones commonly come two ways, heat sealed and hand rolled. Both work fine, though the hand rolled cone takes some practice to secure properly. Cones take a bit of time to get use to but I find they have the widest range. By this I mean you can get more variation in line thickness and dot sizes than you can with other applicators. (Though I have seen some professionals who are very adapt with a squeeze bottle and come close to the same range.) The cone, especially the heat sealed cone, is much easier on your hand, arm and shoulder. If your doing it properly it won't take more pressure than writing with a pencil. This is very important if your going to be doing henna for long periods of time. I believe once you've mastered the cone it's easier to use and is much faster than the bottles.