I've been painting enormous kites for a party. 4 in total - they are painted on Tyvek - the material used to wrap houses - it is very good to paint on. Just regular house paint and a black sharpie oil paint marker for materials. Tyvek is very strong and durable, takes the paint immediately and doesn't rip either, so it can take some abuse.
You can see the skeleton of one of the frames next to me.
here are a couple shots of them in progress:
the 4 kites are: fish, gorillas, jaguars, and hares.
I'll follow up with more pics as they are finished and mounted to their frames.