OK so a rejig with the template and panel pins. Here's how we started.   I removed the pins from the outer ring and left the ones in the Inner shoulder frame - lower outer edge.     I then removed the template and drew around the pins using a flexible metal ruler.     I realised that I should have pinned the inner shoulder frame upper outer edge before I removed the template, as I will need it to check the geometry when fitting the upper strut. I then pinned the inner shoulder frame - upper outer edge.     I then drew around the inner pin marks the same way using a ruler.     I was about to cut the outer shape out but then realised I have not made an allowance for the cladding material, and I don't yet have any as I have not identified what it is I am using.          

Cool, totally understood.

Took off all the hemispheres and sanded the edges smooth, also primed a couple to see how they will look, pretty pleased with the result! More primer and antique gold on the way!  Cut loads of lengths of wood and glued them around the centre section to make a structure for the lower collar. Used some thin plastic sheet to mock it up before making it in wood.   

Thank you for adding it in.   I don't see a typo. Maybe not looking hard enough.