Back in the day, I photographed a lot of parts models. That's what they are called- as in a model whose signature feature is her hands. or her feet, or her legs. Often times, when the work was done they would agree to stick around so we could play in front of the camera. The shape of my model's Liza's nails in the image above is kind of scary, looking at it now. She had the most perfectly tended hands and nails and I appreciated her exquisite care that kept them in pristine condition. I never once saw a hand model manage a phone with her fingers. They wore the best gloves and you always wanted to check out their hand cream.
(I fell in love with Christian Dior nail polish in the 70's and to this day I have a fascination with nail polish as a medium. Sort of amazes me.)