Heat it well with a blow torch. Allow to cool, this will anneal the brass rod, and make it very easy to work.
Find a former (mandrel) of the diameter you wish to replicate. With that diameter of rod, you should be able to bend it round with your fingers. As you work the brass, it will work harden, so just heat it up again if it gets too stiff to work easily.
The ends may want a little persuasion with a plastic mallet (take it easy), then just trim back the rod and solder the ends (I prefer to silver solder thicker brass, although soft solder will be more than adequate).