You'll also need an angled eyeliner brush to apply and mix your colors — don't use an expensive one because it will get covered with nail polish! (teenvogue.com)
Use eyeliner brush or synthetic flat eye brush to apply liquid foundation or concealer. (stylesgap.com)
All you need is a flat eyeliner brush (I use this one) and a little water but it makes it super easy to paint on a thin line at the lashes. (tweedandlace.com)