There are a few mash paddle threads already extant, a simple search of this DYI forum for "paddle" will find them. Some much more fancy designs than my humble effort...
How do you guys feel about mash paddles versus the big industrial potato mashers? Definitely not as cool looking with the designs and what not, sure, but more effective at breaking up grainballs? Probably.
My buddy made mine from white ash. It looks like a big three prong fork and works well. Best thing is, when you go to get the lumber, you can tell Wifey that you're just going out looking for a little piece of ash.