I came across this website looking for ideas, but had an idea for yours. If you got the time to invest the thick leather hides could be crafted into a layered scales of a dragon. I have seen something once that had looked similar.
Anyway, just a thought if you got the time as I said. If not, I have an idea about using either cardboard or rubber foam board. I have constructed several costumes using cardboard and duct tape...the tapes is quite easy to paint.