Inspired by this and many other posts I found looking for recipes, I decided to let Moira try painting on our windows. You know, outside, so I wouldn't get annoyed at the paint getting all over, and naked, so she wouldn't get upset at paint getting all over her.
It started out so calmly, with Moira insisting on using just one color of the three she insisted we make, and painting with a tooth brush.
Then some paint got knocked over, and she remembered that I said she could use her fingers. After trying that out, she wanted to "Stomp in the mud!"
Every time she got paint on some part of herself, she had to wash it off, which eventually lead to a full on bath in her water table, totally her idea.
This whole process, stomp in the paint, rinse off, stomp in the paint some more, continue, was worth more then a half an hour of entertainment. And all the windows she could reach got painted. Also, because it was mostly soap and water, clean up was pretty easy. And it was a bath night, so Moira's clean up was pretty easy too.