Preheat oven to 200°F/93°C. Line 2 baking sheets with parchment paper.
Slice oranges into 1/4 - 1/2 inch thick slices. Place the slices in a single layer on prepared baking sheets.
Bake for 3-4 hours or until completely dry, opening the oven door occasionally to flip the slices during baking. Note that it may take longer if you have thicker orange slices.
The longer you dry the orange slices, the darker color they’ll get. Let the slices dry at room temperature.
Poke a hole in each slice with a pen. Thread the needle with twine and make a stitch through each slice. You can tie the twine to a toothpick and use it as a needle.