I just wanted to say a HUGE THANK YOU to everyone who has contributed to this thread. I have learned so much about PAX and paint.
I wanted to take a moment to share my first face paint test session for my cosplay I'm prepping for first weekend in June at Denver ComicCon. If you can't tell, I'm attending as a Twi'Lek
I have constructed the lekku (the brain tentacles) from polyurethan vinyl fabric, sewed and stuffed lightly. The lekku were painted with fabric paint since acrylic will crack and fall off the vinyl. So to color match, I mixed the pros-aide with the same fabric paint I used on a 1:1 solution. The feel of it is just as you mentioned, like a second skin. I do not feel my skin can breathe perfectly, but I did feel it was possible to stay in the paint for an all day con. I will be testing the acrylic paint for color match and breathability next weekend.
Thanks again for all the fantastic info!