body paint for social experiment?

✨sparkle🐠cubs™️✨ • Twin Momma, 🚨💉💊, married to my best friend, ALLY & bleeding heart liberal!
Hi! So I am mentoring a highschool senior for her senior project...we have a unique bond in that we both have port wine stain birthmarks that are visible, & she has decided to use this as her topic, hence the mentorship. Anyway, she is doing a "social experiment" that involves painting realistic birthmarks on otherwise "unmarked" people & sending them into the world to observe their experiences for a day...she's the most bad ass 17 yr old I've ever met!
Now to my question, any recommendations on what type of body paint might work best? I'm considering red Henna paint, but blotting it with a sponge? Any ideas from you talented beauties? Here's a pic of my hand for reference