I have a piece of plexiglass 24x24 (with tape of the sides so I don't accidentally mark my top) and I place it over a section on my top and use a vis a vi marker (similar to dry erase markers) and I draw out designs until I find what looks best. Inexpensive, easy to do and easy to clean up and the practice helps me with muscle memory for quilting on my longarm. I read this on a longarm board, and when I took a classes from Cindy Roth at Longarm Univesity she also used this method and it works great!!!