This hay feeder is built on site and is impossible to move (rather sad since we don't have any horses there right now).

I nailed a thin board on the wall, with the smooth side into the room. Then I nailed a couple of 2x2 at the sides of the board to build the rest of the feeder from. The heavy frame on top was put there to make it sturdy enough to be filled by the tractor but when I tried the hay got stuck on the way down trough the feeder. It did however work just fine if I filled it by hand (isn't that typical). If you look closely you can see that I have made the front wall leaning to make the feeder wider at the bottom. The feeder is made from form plywood which is smoother than ordinary plywood.

   
 
  The horses have no problem empty it to the last straw and it gives no wasted hay on the ground. Some intelligent guy however, fastened the grid rigorously to make it almost impossible to empty by hand when you have moved the horses to a different location.