How to quickly make a repeating pattern brush from a long image, without wasting your time swearing at the Pathfinder palette.
- Draw a funny little alligator. Or a pickle. Or a snake. Or an abstract pattern. Whatever.
- Make two duplicates of the whole gator, and the rectangles you want to crop it with.
- On the first gator, delete the left and right rectangles. Then select the whole gator and the center rectangle, and do object>clipping mask>make.
- Select the now-invisible clipping mask. Copy it. Deselect all. Edit>Paste in back.
- Select the clipping mask, its contents, and the invisible rectangle behind it. Make a pattern from it.
- On the second gator, do steps 2-3, except keep and duplicate the leftmost rectangle. Make another pattern.
- Third gator, third rectangle. Steps 2-3 again.
- Make an art brush using all gator part patterns.
- Enjoy your gator brush.
(Or make an art brush directly from the art in step 4 instead of making the pattern, set the Brush palette to List View, then alt-drag the front and back parts of the gator into the appropriate slots in the brush instead of making patterns.)
The secret sauce here is the invisible rectangle behind everything. If you have one of these, then Illustrator will use this as the boundary of an art/pattern brush. If you don’t then it’ll use the bounding box of everything, including the hidden clipped parts – make another three copies of the gator and skip step 3 to see this in action. Without the clipping mask it’ll still work but you’ll get the whole gator image drawn along the path, overlapping.
In general I recommend staying the fuck away from the Pathfinder palette, it rarely behaves like you expect it to and will make you swear for hours on end. Use clipping masks/Draw Inside, pattern fills, or opacity masks instead.
Here’s an Illustrator file demonstrating this: gatorgatorgatorgator.ai