Radiasing fender lips

I am looking for info on how to radias a fender lip. I have a pair of 71 Duster fenders that the factory fender lips were cut out of. This was done decades ago for larger front tire clearance. Since duster fenders are hard to find i was hoping I could save these buy radiasing or adding in some sort of small flare. something Like this was done on one of the later Sox an martin Dusters. Any pictures or info would be helpful. Thanks