inspired by Paul's skiddable shelters we decided to make a couple for our sheep.
These are made with old pallet wood and reused roofing/siding/metal stuff. That basically determined what size they would be. That and the width of the gates.
They are bottom heavy so the sheep can't push them over. They are also light enough that one strong person can pick up one end just enough to nudge it into place.
We've moved them a few times, this last time one was a bit stuck so when we attached the tractor to the tongue it split the wood we used. Something to repair before the next move. But that's okay because we had this old bit of rope and just wrapped it around the base and tied it to the tractor. Worked like a charm.
On the whole, we are very happy with these and plan to build more this fall.