I made one several years ago, I came across some conduit, excess on a job I was on. It was 10 ft long. I made 2 squares, and cut some conduit in half, and welded one square on top of the other. That made it 5 ft high. Then I closed 3 sides in with heavy woven wire fencing. I made a bar to adjust height on the open side. Fastened a feeder across from the open end with a hopper. I then added a bracket to move it with my 3 point hitch. It works good, but I found I needed a roof over the feeder to keep rain out. I only use it when the grass gets short in late summer. It was easy to build, and the price was right.