Two pieces of 1" x 6" poplar dowel. Drill a 3/8" hole in the end of one and one 3/8" hole and one 11/32" in the other. Open the two holes in the second dowel out to the side.
The dowel with the single hole is for field points. The one with two holes for broadheads or other arrow points the first dowel won't slip over.
To use, look down the arrow and place the tool at the kink. Use enough pressure to bend it back the way you want it. As an alternative, set the shaft with one end on a table and rub the high spot hard with the tool. The heat from rubbing friction and pressure will work the bend out. It takes a bit of practice to get a feel for what the wood will take. Practice on a dowel or broken arrow. If you have a way to apply heat it will help the set take better. I warm the shafts over a paint stripper gun held in a vice.
Bend in the fletch area? Use the larger screw eye cemented in the tip of the dowel with one hole to slip over the feathers and apply pressure with that. These work great and go back to antler and bone tools used during or just after the ice age.