That s/s is pretty tuff stuff. You could use heat, although I've found it work hardens really quickly (304) after it's bent. If you're cold bending, it would be advantageous to have extra length on the stock to bend it with. How accurate is "accurate"?
40 x 3 Stainless is easy to bend, how many are you doing, if its only a few you could make a template or mark it out on a piece of sheet, and bend it in a set of horns, which is just two pins welded to a plate, you may want to make it slightly longer and trim afterwards as you will get a flat right on the end, heating it is the last thing you want to be doing, if you have a larger quantity to do a ring roller is the way to go.
These were bent by hand in horns,
Got it done, took ages bending and pinching it in a vice and by hand. Having it all tig welded together by a friend of a friend and dont want any reason for it to be done badly.