Sawing Through Steel
A sponge "plug" can make sawing through a metal door much easier
Need to drill a large-diameter hole through a metal door or stainless-steel sink? You'll need a hole saw. The tiny teeth on this tool are specially engineered to cut through the toughest materials. Unfortunately, the heat created by the spinning saw dulls the saw teeth and discolors the workpiece. That means you'll need to lubricate the saw as you go. Here's a neat way to do that without growing a third hand or calling on some outside help:
Use the saw to cut through a sponge. Then remove the "plug" from inside the hole saw, soak it in cutting fluid or machine oil and slip it back inside the saw. Oil will seep from the sponge as you cut, lubricating the surface as it helps keep the saw cutting cooler and quicker.