Start by enlarging the Canvas to a decent size. I was aiming at 1000 x 1000 pixels but I now realize the image below is over 2000 pixels square
- Enlarge the shape to nearly fill the canvas so we can use it as a tracing aid. Free Transform
- Create a new layer between the BG and shape layers and use the elipse Marquee too to fit round the outer elipse in the center of the shape. Fill your elipse in the new layer with Black (any colour other than yellow will do).
- reselect the marquee tool, and Ctrl (Cmd ) click the black elipse to load its selection.
- Now move the marching ants to the right (you must start with the cursor inside the marching ants) until its outline fits inside the shape.
- With the black elipse shape layer selected, press delete to remove the unwanted pixels. You now have the center part of your shape.
- Copy that layer, and use Free Transform to make it fit the upper part of the shape. Copy that layer
- Use Free Transform and right click and choose Flip vertically. Move to fit the laower part of the shape.
- Select the three black shape layers, and merge them (Ctrl e)
- Ctrl click the new shape layer to load as selection, and go to the Paths palette. Click on third icon from right too make in Work Path
- Save the path (from fly out in top right corner of Paths palette.
[EDIT] I have downsized the shape graphic now.
Thank you for your help, I will try to do this and let you know how I made out.