Diane Salter - A New Step-by-Step Tutorial for 2015 including the use of Gelli painted papers! And then I cut up the blocked-out segments of the cat and numbered them--making it much easier to cut out the same pieces with my paper--
To print on a paper bag, invert the image (across horizon), click on "Custom" and enter the dimensions (5.2x10.2). Rename the custom print, "paper bag". Hit OK and you're all set. Next time, you'll just have to go to paper size and select "paper bag".