I have a number of paint boxes that I use. This one is a heavy metal black enamel version made by Winsor & Newton. It comes with a built-in water container and a metal water cup that attaches to the side. The lid acts as a small mixing area.
I have modified it in a couple of ways: First, I removed the metal brackets that go between the paint rows. I had a friend make some metal spacer bars to take up the extra room. (After a while, paint and water spilling out beyond the pans acts as an adhesive to keep the pans in place.)
The next modification was to take out the half pans that come with the set and put in my own paint. I use Holbein tube paint. I squirt it into the now empty half pans and let it dry for a few hours. My colors are as follows: Permanent Alizarin Crimson, Cadmium Red Light, Permanent Yellow Orange, Gamboge Nova, Raw Sienna, Burnt Sienna, Burnt Umber, Greenish Yellow, Cerulean Blue, Colbalt Turquoise Light, Marine Blue and Ultramarine Deep.
It is a perfect small paint set and suitable for doing casual sketches as well as large paintings.