Here is a pic of one of my forms for recurving tips. I have another a bit more dramatic but not so much as JustAin's.
I use a heat gun and oil on osage. Any veg oil will work. Having a metal support band tight against the outside of the curve will help prevent splintering. Generally I will have the form set up in a vise at about a 45deg angle, oil the bow and place it in the form and secure the support band. I begin heating the area to be bent and when gravity begins to pull the bow down, it is hot enough. I pull the bow down to the form, adjusting any twist and clamp it in place. If there is any additional twist in the tip a wedge here or there will help. Let it cool overnight and work the other tip.