Look at this great examples of kid's creativity.
Plastic bottles: pieced of bottles + caps.
Coca-cola cans flattened, painted, see on the edges of the tree those little thingies used to open the tin.
Foreground: used espresso coffee capsules, flattened.
Background: cut foil.
Foreground: CD's + metal wire.
Used latex hand gloves, foil + paper cut in gloves' shape + plastic bottles + coffee capsules.
Cut foil.
Bottoms of the plastic bottles, painted.
