I cut some rugged ridge oem style flares flat to see how I would like them. They are 7" wide to begin with and I cut them to 5". I made measurements from the body and marked a few locations, then ran plain masking tape across to make a straight line. Used a oscillating tool to make the cut. Not perfectly smooth but if I decide to rock them the line could easily me smoothed out with a little sandpaper.
Third pic is random internet pic that was my inspiration. That owner put door trim on the edge and sprayed them with bedliner paint.
I trimmed 1.5 inches off mine. I wanted to keep the side marker lights. So I cut a block of wood to use as a guide. Just left it sit in the sun and let the plastic get nice and warm.
Before