Shabbat 64 - Ornaments of a woman on Shabbat
A woman may go out on Shabbat with her hair braided with strands of other hair, whether the strands are of her own hair, of her companion, or of an animal. All parts of this ruling are necessary. Otherwise we might have thought that her own hair is acceptable because she is used to it, but not that of her companion. Or we might think that human hair would blend into hers, whereas the animal's would not, and she might then take it off and carry - so the ruling tells us that there is no such concern.
However, a elderly woman should not go out with strands of a young woman's hair, nor the young woman with the old one's hair. Here we understand the first part: they might mock an elderly woman for her attempts, and she might then carry the strands, but why would a young woman wear the old one's hair strands? - In truth, she would not, but the ruling just mentions this possibility for symmetry.
A frontlet or head bangles can be worn when sewn into a woman's hat - because she would not take the hat off in the street and uncover her hair. A woman may go out with a wad in her sandal, for comfort, or with a peppercorn in her mouth, for pleasant breath - provided that she puts these in before Shabbat, for otherwise the onlookers may think that it is just a design to carry in a public area.
Art: Albrecht Durer - The Furlegerin with braided hair