I have six sections I bought last fall from the man who built them and only used them 1 tear before dispersing his herd.He used lots of old grader blades and oil field tubing. and real nice round edge boards. The are movable but not as portable and Per's and Grassfarmer's.
I like to put them at almost right angles and they chain together.
He had extra grader blades that bolted on the feet on each side for stability but they have stood very well being joined at a angle.
The tabs sticking out the back are what you hook your front end loader bucket onto to lift them. I can lift them to clear a 8ft fence.
These two are in the back yard keeping snow off the road. They sure worked.