What you need:
string (or twine)
glue (I used Drvofix)
golden/silver spray paint
wooden beads, pine cones, dried lemon/orange slices, …
Blow up the balloons to the size of your desired decoration. Place it on top of a glass jar.
Dilute the glue slightly with water in a small bowl. Dip in a piece of string (1-2 m long, depending on how dense you wish to wrap it) in the glue.
Removing any excess glue with your fingertips (use rubber gloves!) wrap the string around the balloon. Check whether the string is glued to the balloon – apply more glue if needed, in particular for gluing the string ends.
Leave to dry overnight.
Once dried and hardened, pop and remove the balloon. Place the ornament on a large sheet of paper and spray all sides with the spray paint. Place on the glass jar to dry.
Use your imagination to decorate the ornament with beads, ribbons, pine cones or dried fruit.