They are often small, ( the name derives from the French for "pocket" ) although they can now be bought in all sorts of sizes and designs.
I made mine from the remains of an old wardrobe many years ago when pochade boxes were much rarer, but by making my own, I was able to incorporate all the things I thought most important.
I decided that the box should be small so that I could make quick oil sketches and even use it when sitting in a car. So I settled on a painting panel size of 7 x 10 inches. In order to make sure the panels I would be using would fit, I made the lid first and routed out three slots so that the box would take up to three panels.
I then made the storage part of the box to fit.
I like the idea of a sliding palette rather than a lift-out one which some boxes have, which means having to find somewhere to put it.
I designed mine to hold everything necessary.
If you are making one, make sure you allow enough space below the sliding palette to hold what you need.
Also be sure to allow sufficient space between any wet painting that may be in the lid and the wet paints on the palette so that they do not touch when the box is closed .
This is my pochade box when I first made it.
The front section with the handle is hinged at the top and can be folded down when the box is in use. This makes it easier to use the paints.
When the painting is finished, the lid is closed with the painting still in it, and the hinged section is also closed and clipped into place.
The flap folded down can be seen more easily in the picture of the box in use at top right.
I try not to put more than is necessary in the storage area under the sliding palette. A few tubes of paint, a couple of cut-down brushes, a dipper for thinners, a cloth, for example.