The Hole Troll is a brilliant product to keep in your toolbox that can help you enlarge existing holes with far less frustration. Center the guide over the hole, fasten it in place (nails, screws, hot glue, and other options all work), line up your hole saw with the groove you need to cut, and pull the trigger. There’s no need for a pilot bit—the Hole Troll keeps you in line and stable. With a 6-pack costing just under $20, there’s no reason not to have the Trolls working on your side for once.