You can use a caul as well, of any shape. Doesn't have to be curved. A straight 2 x 4 or whatever, 36" long or longer, would do. Just need something to hold a clamp. Heat the wood with a heat gun, paint stripper. If you ain't got one of them, a 1500 watt hair dryer would probably work but it would take a while longer. And some risk of burning it out. Probably cheaper to go buy a heat gun for $20, versus having yer wife mad at you, and then have her spend $25 on a new hair dryer. LOL
You can heat the wood with anything, your kitchen stove. But you have to get it into it's new shape fast, within 10 or 15 seconds of removing from heat.
This is osage but hickory will work as well or better. Use a good long heat soak, 5 minutes. You want it heated through, not just on the outside. Also be sure you wood is fairly dry, seasoned for tillering. Wet wood will check if you use dry heat, but can be steamed.