From page 4 of the link above...
Raśl Musibay: We use poles and mesh from a standard chain link fence.
Glenn Lindgren: We use either ALUMINUM OR ALUMINIZED chain link fabric (aluminum-coated steel mesh) for all surfaces that come in contact with the pig. WE NEVER USE galvanized metal!
Jorge Castillo: We lay the poles, which are galvanized metal since they never come in contact with the pig, across the top of our blocks to get an idea of the correct size. Then we cut two sections of wire mesh to size.