Here is a photo of the finished colour exchange that I did (courtesy of Rachael as I forgot to take one before I posted it). Rachael loved it and I'm pleased with how it turned out too.
I decided to finish it as a notebook cover and I think it came out ok. The hardest part was figuring out how to hem the edges without making too many layers or without showing them (as they would be seen when the cover was removed to put on a new notebook). I finally settled on putting bias binding around the fabric.
Then it was a simple matter of lining it up and sewing four little seams to create the sleeves. Unfortunately I did end up with a bit of bulk in the corners there, but I'm not sure there is a way to avoid that. I suppose putting some padding in would bulk up the rest of the cover so the corners wouldn't be as noticeable - might have to try that next time. Then cover it with lining and it would solve the hemming problem too.
Here is a picture of the pattern I started out with (from an old magazine called Needlepoint Gold):
Quite a difference in the end. I knew from the start there would be changes as I wanted a different colour (forest green) and I would be doing it in stranded cotton on 28ct fabric, rather than wool on 14 count monocanvas. As it was mostly satin stitch type stitches I was hoping I wouldn't have to alter too much but would just be able to add extra lines in for the extra holes. I was also going to continue the triangles on the edges to turn them into diamonds and create flaps to close up on the back. But mostly it looked wrong, so apart from the very centre stitch and the two diamonds everything else changed, including the finishing.