I'm really paranoid about what I put in my hair, but France Luxes has some tiny tige boule barrettes that are very gentle on hair and work really well for what you want. They won't hold a whole lot of hair, but I find this actually works better, because they don't mess up curl pattern. They only come in colors, but they're pretty subtle.

France Luxe Mini Volume Tige Boule - Barrettes - France Luxe Accessories
3a/b, fine, normal porosity, high density

Wash: CJ Daily Fix, As I Am, TJs TTT
RO: YTB
LI: Suave TC + CJ CCCC, brushed through with Denman
Styling: Smooth in LAL Wet Look gel, scrunch, and plop 10 minutes, then add a little more gel, cover with silk cap, and sleep on it
Refresh: 3:1 water/Suave mix as needed