Here are two of the feeders that I am using with my flock of Border
Leicesters. It's not a perfect system, there is some waste, but not
a terrible amount and more importantly, this keeps most of the VM out of
the fleeces, except the top of the neck.
What you see here is two feeders side by side. One is 8' and the
other 6', just because that's what fits here in my barn. You can
make them any size you need. The feeders are only attached to the
combo panels by baling twine. They can be taken down and moved to
any hog panel or combo panel where I need them.
Since we run pigs in the barn after the sheep go out in the spring, this
means I can move the feeders out of the way of the pigs. That
also means that what waste there is will be eaten up later, but the pigs
:)
You can see that I used just a very flimsy 1/4" plywood for the backing,
if I was buying materials, I'd get 1/2", but I had the 1/4" laying around...
My 2"x 4" are all actual size, we're lucky to have a rough-cut sawmill
Amish neighbor :) But standard 2"x 4" will work fine. I ran
one along the bottom for the flakes of hay to sit on. The 
others are just for supports.
Sizes would be depending on your breed, I guess. I wanted that
bottom board about even with the bottom of their necks on my BLs. It
seems to be working fine. They don't get wool out onto the backs
of their neighbors this way.
I think part of why these work so well is that the sheep do not have to
put their whole heads in the feeder. Only their noses poke in to get
a mouthful of hay. That doesn't allow the hay to get in a position to
be pulled out in large bunches and dropped on the ground or a neighbor. The
back is close enough to the panel that wide flakes don't settle all the way
to the 2"x 4" bottom until they get eaten away a bit.
Sorry I don't have any real "plans", I just cobbled these together and
I like them! I used to use a similar feeder, but it wasn't portable.
This is better.
