I used 1/2" dowels cut exactly to the width of my screen cage, and put thumb-tacks, pushed into the ends from the outside of the cage, into each end of the dowel. So far they seem to work great! Worst case, the dowel falls, but the tack on the outside of the cage will fall to the floor, not inside the cage.
My 1 yr big veiled uses them and so far so good! I even have big fake vines hanging from them.