I have decided to create my own template for our sleeve, as the one I got from the internet did not fit our cup correctly. At first I wasn't sure how to go about it as I didn't know how to calcite the exact curves. I found out that outer layer peeled off which was a good starting point.
I then took my scan over to Illustrator and traced the outline. I didn't want our sleeve to be as tall so I edited it to be smaller while still retaining the original form.
After printing it off I was pleased to find that it fit correctly. Around the back it was slightly wonky but I think this was because of my incorrect cutting.
To develop it further I tried to add an additional shape to the outline to add an interesting look. I used guides to help get it central and I also had to consider the height of the ark so it didn't protrude or come to close to the top of the cup.
I think this template has worked really successfully and adds another level to the design. At a later date I may develop it further to work with other aspects of the composition.