I like bees. I like to paint. Why not paint on bee hives?
I love painting on wood, so every hive presents me with a blank canvas.
I like the look of the bare wood as well so I leave most of my box surface unpainted. Where I do paint I use non-toxic acrylic paints and cover the work after with Chapman's Beeswax Salad Bowl Finish. As to leaving the rest of the box unpainted, I like this quote by Richard Taylor, from The Joys of Beekeeping.
"The hives need no painting, although there is no harm in doing it if their owner wants to please his own eye. The bees find their way to their own hives more easily if the hives do not all look alike. I rarely paint mine, and as a result no two are quite alike. Most have the appearance of many years of use and many seasons of exposure to the elements."