Courtesy : http://www.vecpix.com/tutorials/illustrator/il023.php
Our technique for creating Art Brushes involves three major steps: the creation of the “nib,” the conversion of the nib to a brush and the archiving of the brush for future use in any document. We’ll cover all the basics, so you shouldn’t need a refresher course before we get started. But, if you do want some additional material on Illustrator brushes or, if you’re interested in creating Pattern Brushes as well, you can find Part 1 of this tutorial series here.[an error occurred while processing this directive]Creating the ‘nib’
All good art brushes begin with a good nib. You can think of the nib as the pattern a bristle brush would create if you were to load it up with paint and press it straight onto your canvas. But instead of bristles, our nib will be composed of small vector objects shaded to produce variations in the stroke. This nib, when applied to a path, will be stretched out to produce the illusion that the paint has been applied with a brush. So what is a “good” nib to use with an Art Brush? The shape of the nib itself is unimportant. The key is complexity. The more complex, the more detailed the object we use for a nib, the more “natural” your brush will look. (Not that there’s anything more natural about chemicals synthesized in a lab than pixels displayed on your screen. But you get the idea. We’re going for the look of paint here.)
There are several ways to create nibs, of course. One, which I use all the time, is to generate a textured shape in Adobe Photoshop, convert it to vectors in a program like Macromedia Freehand or Creature House Expression and then bring that vector file into Illustrator for use in the brush. But for this tutorial, we’ll assume you don’t have access to that kind of firepower. So we’ll produce everything within Illustrator itself. With this in mind, here’s one way to do it.
1. Select the Ellipse tool, and tap it on your canvas to call up the Ellipse dialog. Enter width and height values of 100 points.
2. Set the fill of the circle you just created to a light gray. Set the stroke to “none.”