Plans for building horse hay feeders are available at Horse Nation and include trash can feeders, tub feeders and wall rack feeders. An individual can also make feeders from a water storage barrel by cutting off the bottom of a barrel and attaching mesh wire.
A water barrel can also be cut in half lengthwise and mounted on a wooden frame. One half nestles at the bottom of the frame for the hay trough, and the top half is positioned above to protect the hay from rain. To turn a trash can into a feeder, cut a few small holes in the bottom so that the horse can reach the hay, and attach the lid on top.