IOM mast bending jig using these U-groove rollers from Amazon:
https://www.amazon.ca/gp/product/B07…?ie=UTF8&psc=1
I built it with 3 possible outer roller settings, 8, 10 & 12″ centers. This is setup for 12″ centers.
The lever pivot has 2 additional holes to move it for the 8 & 10″ setup.
I have not yet used this, but based on other designs, it should work quite well.