Creating the design in a computer would relatively be way easier than cutting pieces of art paper. Just open a photo editing program and shape away! Knowing what a flower would look like, you would only need to combine shapes and designs along with a nice background for you to create the perfect design for your flower wallpaper border.
If you have access to the internet, you can even search for generic artworks of floral design! Take these designs to your photo editing program and you just basically have to fit the design to a fine strip of paper. Be sure to use the proper paper to use when printing. It is recommended to use a glossy paper to maximize that professional look and feel to that flower wallpaper border.
Additionally, you must also cut the design symmetrically enough to create the repeating design pattern for each sheet of paper that you are going to use. This way, even if you line them up in your wall, they wouldn’t look very loud and gaudy and would just mimic the design of commercial flower wallpaper borders.