I recently purchased a rostte die from MFT, and I love it. You can, of course make your own rosettes as big or as small as you like, but if you are in a hurry (usually me) or lazy (also usually me) this die will save you time. Its six inches long, so you will have to die cut 2 of them to make one rosette.
If you want to make your own rosette, just cut a long strip of paper about 1- 1 1/2 inches wide and about 12 inches long. Using your scoring tool, score lines every quarter to half inch, depending on the width you want. Do this all the way down the strip, making sure you score along the short end, so you end up with many score lines. Then, just fold them back and forth all along the strip till you get to the bottom.
Attach the ends and you have a rosette! Here is the card I made for my niece Jacqueline a few weeks ago. It is so pretty and colorful in person. I also thought that her Mom could use the front of this card on a scrapbook page celebrating her day, so I didnt add anything else to the front.