For eyes, I like to use small pearl beads. Just dab some paint on the eyelet hole however you want your character’s eyes to look. blue, green, iris, no iris, big small….or better yet, make many designs so you can animate them!
Why paint the eyelet and not the smooth part of the bead? answer: eye mobility. by using the eyelet, you can animate eye movement easily using a small pin. Just insert the pin into the eyelet and drag the pupil whatever way you want your character to peer!
here’s some pictures of me painting a set of 12 or so beads that will animate to look like a small red pupil enlarging to a large bloodshot eye.