Most portable easels lack a tray to hold drawing or painting materials.

Here is a design for a homemade tray that simply fits over the front of an upright easel and wedges into place. It is quite sturdy and not large or heavy enough to tip the easel forward.

It is cut from medium-density fibreboard, 32cm by 40cm. The size of the cuts into the board for attaching it will depend the dimensions of the easel legs. What holds it horizontal are the pieces of timber glued on the underside of the tray, which cause it to wedge firmly against the legs. Holes have been drilled to hold brushes.

Maybe an inventive person can think of more or different features!