Hi Suzanne:
Yes I used the pattern from RJ Designs Roma Lambson that Nancys Notions carries. In the pattern she gives detailed instructions on starting and stopping as well as how to make it longer, narrower, rounder. In my opinion it would be easy to make one to fit the space. The quilt shop I purchased the pattern from had a small completely round one on display. She also has a pattern out that makes a rectangle shape but I think that one will need binding on the ends but would be easier to get the exact size you want. I see that Nancys Notions has that pattern, I may have to purchase it too.
My mom has one of those gravity lounge chairs and when she saw my rug she said that would make a great cushion for my chair. I think she is onto something and with that subtle hint, motivation in getting the rectangle pattern was formed. She is 88 and I try to provide whatever she desires......lol