Allrighty then, here's a few pointers for those who get a wild hair, and decide to sculpt your fender.
First you need ventilation. I used my paint bay and turned the exhaust fan on. I'm sure I'm going to regret it.
Second, you need a respirator, goggles, gloves, hazardous material suit. Damn I hate fiberglass.
I used a diamond cut wheel for my dermal, to cut it, leaving about 3/16'' from my line.
Then I used a barrel sander to take it out to the edge.
And measured it out as I went to make it even all the way around. And I use a small carbide bit to get up in the corners.
My next step will be to spread some kitty hair on the inside of the fender, to give it some strength. Then I'll come back and round all the edges.