If you are going to mess with old tool boxes make yourself a pair or two of these:
The basis of these are dead. chipped, live wire blasted, nippers, and smallish, but heavy angle. You need to notch the angle to fit the gullet of the jaws, and grind some off the jaws for a decent handle angle, then clamp some sheet metal in the jaws and weld them up. the sheet metal gives you the proper spacing, otherwise the don't close well at the tips.
With these I can take out all sorts of whoopees and kinks on box/tray edges, and its dead easy. The short distance to the pivot makes them grip very hard, and that is why I like them better than traditional sheet metal tongs.
I can also clamp small bit of metal, adn bend it adn tap on it for a nice sharp bend. I get more use out of these than any other sheet metal tools I own except for snips.