The Spine

Using a similar design to the photos from the web, the spine of the dragon is 4" flex drain tube. This works well allowing the body to flex and move easily while being supportive enough to span between the puppeteer locations under the tail, back legs, front legs and head. I cut a hole in the bottom of the tube for the PVC structure at the front and back legs to fit in.

IMPORTANT NOTE:
Later on I had to go back and reinforce the spine and the front and rear leg connections. The weight of the fabric was too much for the flex tube and it looked like the dragon had a back problem. I went in (looking like a dragon proctologist) and added in a length of PVC to reinforce the connection across the back. I highly recommend doing this before adding skin to the dragon.

The spine curved too much behind her hips.

I highly recommend doing this before adding the skin to the dragon.