I would cut a jig using the other side as a model for both inner and outer curve, then use bar clamps to clamp the jigs on and slowly tighten it over the course of a few weeks. if when you release the jigs is spring back bit you can exagerrate the curves a little so it ends up more curved when jigged but will spring back to the desired curve. using boiling water to soften it while tightening may speed it up a little but you don’t want to flex it too fast and crack anything.