Here’s a thing I’ve been kind of wanting for a while, and finally nailed: that dotty, super-spitty-airbrush look.

Draw a black circle. effect->brush stroke->spatter, play with the parameters until it looks good object->expand appearance object->image trace->make window->image trace, play with the parameters until it looks good object->image trace->expand drag into brush palette, make a scatter brush

All the brushstrokes in that screenshot are done with the same green with varying opacity settings: 50% for all of them, normal/screen/multiply mode.

You probably shouldn’t try to fill in a whole image with this as things would get pretty slow to render; use it to create accents.

You could try different starting shapes and different effects – maybe a triangle that’s been put through the ocean ripple effect is just what you want. Kinda looks like a lot of messy angular brushstrokes, huh?

Or how about if I add a ‘roughen’ effect to the paths I drew, on top of using the scatter brush?

Wow, it sure looks like I made a lot of twitchy little brush dabs there, doesn’t it. Thanks for doing the work for me, Illustrator!

Edit, some time later: Or how about that oh-so-coveted spitty airbrush look? Seriously, I see people asking for that one all the time.

Caveats: You don’t want to try and draw an entire picture with these kinds of brushes. Illustrator will slow way the hell down. Lay in flat shapes with simple filled paths, then come back in and paint highlights/shadows with your Messy Brushes.