Thanks Robin for the tip. This is such a cool project. Cost of material - less than the cost of a new bean bag; Fun and laughs you'll have doing this project - priceless!
Tips for felt: Try a quilting store for your felt. Often they have fat quarters available in a variety of colors. The quality is much better than craft felt and the colors tend to be more subtle and sophisticated than the stock primaries that the craft store offers. Click on the bottom image to have 8.5 x 11 printable instructions.
Allison's pattern available for download at Petit Elefant.