A particle brush of bobby/hair pins. There are multiple styles and types, but this is the first one I've made of them and these are the ones I see the most often.
I completely free-handed these (no sketch--I went straight to lineart), so they're not perfect, but hopefully they're good enough for others to use.
Feel free to adjust the settings as you need. The brush tip images themselves are white with very light gray tips. This is so that you can overlay whatever color or tone you want more easily.