Keep an eye open around construction sites and building supply warehouses for a cheap (free) source of stiffening in the dump bins or just lying about. The stuff they use to bundle wood and pipes (and all sorts of similar goods) comes in plastic and metal, the metal is sometimes painted and sometimes just 'blued' to stop rust - if it hasn't been stored outside for a long time the metal strips will be rust free and can be used for quick projects like skirt hoops or bodice boning, and if you give it an extra coat of suitable spray paint it is good for more permanent projects. The plastic version comes in a couple of thicknesses & widths, most is only suitable for light duty such as children's costumes or stuffed toys (not as strong as what your dragon uses).
Around here it is commonly called 'Band It tape' - when I first heard it referenced I though they meant 'Bandit' (thief) tape - it used to be commonly used by car thieves to open doors before fully integrated electronic locks on cars became common.