With the aid of some photos, I sent some pictures showing the measurements I needed. Before I could make these in the chosen fabric, I needed to make sure the measurements were correct and everything fitted as needed.
I made some out of some curtain lining I had in my box, this is a square one. I also made one to fit the circular arm too, but forgot to take a photo. These then got sent to Scotland.
I receive a message yesterday. They'd arrived and fitted, no alterations needed. This week, I can go and find some fabric and get them made up. Let's hope the real ones go together as easily as these.