UPDATE!

Here is the bigger version. Unfortunately the new Kam Snaps which the postman brought today, are not long pronged so these popped off as soon as I unfastened it from round my wrist. Glad I only risked one!

I wondered if it was possible to make a zipped purse with a zip that didn't go the full width.
It is.
This was intended to have snaps on the ends to fasten around my wrist, but it isn't quite long enough. Back to the drawing board!