From the website Simply Recipes:
Put each stick of butter needed between two large pieces of wax paper. Using a rolling pin, press down on the butter. Roll it out the way you would roll out a pie crust. When the butter is about 1/8 to 1/4-inch thick, lift off the wax paper and peel away the butter--before it gets too soft to peel.
(This reminds Liz of pounding cold butter for the ATK test recipe for croissants...)