I've had two runs, the first one a little one, the second a big deluxe version, and they were both much the same. Maybe this will help people for ideas:
It's basically a bit rectangular wooden frame, covered with chicken wire on the top and three sides. The fourth side is closed in with plywood to make the back wall of a house. The house also has a raised floor and plywood roof, all attached to the frame. The wall which faces the inside of the run is a long door, hinged at the top and bolted at the bottom, with a gap at one end so that pig can get in and out when it's closed.
The house gives shade or shelter and a bit of warmth (you can put hay in there), and catching the pigs is dead easy - when you approach the cage, they will run into the house. Then you just tip the cage up - gently- so that the back wall of the house is on the ground and the door is on the top. Then you unbolt the door, reach in and pick up your pigs.
What's more, it's really strong and quite heavy, very good against predators, of which our worst were cats and foxes. I'd never put a pig on a lawn in an open run. It only takes a minute when your back is turned.
It works really well. We got the idea from Olga da Polga (the door was our own embellishment).