I'm working on a -8 Showplanes fastback top forward fuselage skin modification. We whack out a huge section of that top skin. Of course, the opportunities for cutting too far abound with this kind of thing. Kind of like trimming the canopy. So, the plan is almost always to sneak up to the line. Big cut, little trim, smaller trim, nibbler, rotary file, sanding drum, hand file, scotchbright wheel. Well, I was around the nibbler area of this process. I had about a total of 1.5^2" of material to take out of the skin in two large radiused corners. I quickly pondered the appropriate tool, and loaded up the air nibbler. Now we all know that this can be a very dangerous (to the material) and crude tool when operated free hand. I began my task, very, very carefully, being sure to maintain control. We're within 5/8" of "the line" after all. After about only four seconds, I stopped, to find that little voice in my head screaming very loudly to put this tool down and step away from the part! I heeded my own warning and holstered the tool back in the drawer. Right next to it was the appropriate tool for the task. The hand nibbler. Crisis averted.
. I ultimately selected the correct tool after my four second lapse of choosing "more power".