In addition to what the others said, you can buy a jig that fits on your drill. It makes it look like a router, except that it slides up and down, whereas a router has very little depth adjustment. I bought one years ago, and I can't even remember where I got it, but it wasn't very expensive. I think it was like a True Value Hardware or something. It will enable you to, for instance cut a perfect hole to receive a door latch assembly.
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