At last, after a lot of difficulty turning the strap, I've finished this upcycling project.
It started life as a pair of outgrown and worn on the knees embroidered trousers which I didn't want to throw away. The lining is from an old skirt and the velvet trim removed from another garment.
All I needed to finish was sew the inner and outer 'bags' together and turn - and this turning went relatively easily.
The only little job left is to find a toggle to fasten through the velvet loop. I definitely have several with a natural wood finish but 'think' I have a bright pink one which would look better.