There is no substitute for really great brushes when creating art in Photoshop and Painter. Making your own brush variants is simple, and is explained in several exercises in Beyond Digital Photography.
Though these brushes are not needed for any of the projects in the book, we're providing several custom brushes here for your own brush libraries, including the Bubble brush used in Chapter 8's Simulating Reality Using Compositing, Masking and Color Layers. These brushes are a gift to you as a "thank you" for purchasing the book. Be sure to read the included ReadMe.txt files for complete instructions on how to load brushes into your Photoshop and Painter libraries.
Note: Painter brush installation can be frustrating! The ReadMe file included with the download has been carefully reviewed and tested for Painter 9-11. A wonderful shareware utility for loading Painter brushes called Studio/Chris Brush Manager can be found here.