We have wooden pallets that are made of 4x8's and 2x6's and weigh 400-500 pounds each. They are about 4 feet tall and 16 feet long when stood on one edge. You stand up all four and screw them together. Then we cut one section open for a half door so we could get in, but the pigs can't get out very easily. We have a heavy duty lock to keep the door shut. In spaces in the centers of the pallets, we dropped 2"x16" concrete blocks in in their ends so as they root, the blocks keep dropping down and no one can escape underneath the edges. On the inside, we put chicken wire when they were little so they couldn't fit out from between the 2x6's. Now they can't fit out, but it still helps with the chewing on the wood. My husband built a trough with a chute so we don't have to enter the pen to feed them. You just drop the feed/bread/slop in the top and it ends up in the trough. The trough/chute would probably hold about 1000 pounds of feed if needed. It is huge. I can take picture tomorrow if you would like.
