How to fix a metal futon?

I put together a metal futon earlier today and I am missing the two stretcher pieces that kind of stabilize the frame. They stretch the long way across the futon and attach to both legs of the futon. I was wondering whether or not anyone knows of a good way of making makeshift legs. I was thinking about possibly getting metal rods as long as it and attaching them with L-brackets but I need some more advice. Thank You.