To cut a matching hole in the wall you can use a keyhole saw like this, or—my favorite—a a spiral saw like the RotoZip. (I always jump at the chance to use a power tool.) ...

Saw different I’ve been hanging out with serious craftsmen/carpenters and virtuoso builders in Canada and ended up buying 4 different Japanese saws they were using. At top is a gem of a keyhole saw.

Seriously, ditch the kitchen knife. 1. For the lid and simple cuts: keyhole saw Image: All About Pumpkins The simple keyhole saw is invaluable for basic pumpkin cuts, such as the picture above.