During some seed trials, I made 16 cages out of concrete reinforcing wire they worked great, the square holes were large enough to get your hand through. The only problem was that once the plant got large enough they acted like sails when the wind came through. I originally used only 1 rod of rebar sunk approx 2 feet, after a storm came though I had to up the rebar to 3 per cage. Overall worked great.
