I too have lots of stones... and at first I thought I was going to build a larger run area with a stone wall about two feet high and then build the wooden frame on top of it like I did with the existing stone wall. After lots of thinking and about two hours of digging and placing rocks, I decided the existing stone walls would give enough room for my small herd. I also gained alot of respect for the Basques who built my house, barns and all the stone walls. I did learn somethying interesting though.... when they would cut a small road along a hillside, or carve out a hillside to build a barn or house... BINGO, there were your rocks.
Pete