Plywood would not last the season. T posts only might work if very firmly anchored. You can use things that are WELL out of the pigs reach. With a tiny area (we had 1/4 acre for our 2 pigs) they will get bored fast and that's where the trouble starts. They even managed to get a hold of the tarp over the piggy dripper and pull it down. I have no idea how...as pigs don't fly....