Hens can be easily upset if things deviate from the expected norm, therefore they should never run out of feed once laying has begun. Taking this into account I built an efficient automatic feeder that is simple and inexpensive to construct.
Dimensions are flexible, but the one I built is 27 inches wide, 24 inches high and one 2×4 in depth. Other materials needed are two pieces of 1×6 27 inches long, 3/8-inch plywood for backing and front, 2x4s to go around the outer edge and an old door hinge, plus nails.
The objective is constant feed availability without overflow. I installed a 2×6 board angled 45 degrees at the base of the reservoir with the bottom an inch below the top line of the front-facing 2×4. This gives hens ample pecking room while feed is being gravity funnelled into the trough. No spillage, yet steady supply.
The 2×4 lid is attached on one end with an old door hinge. The weight is sufficient to keep it closed. I separated the tank into two sections to accommodate more than one type of feed simultaneously.
The photo shows an upper lip — the feeder may be attached to a wall and easily removed for cleaning. †