I had been wanting to make butter for quite some time, so one day in the kitchen I thought to myself "what if I just whip the heck out of some whipping cream?" Turns out it works just fine.
1 L of whipping cream (I use Dairyland - Old Fashioned).
Whip cream using electric mixer (handheld or stand) for 10-15 minutes or until butter and cream seperate. Strain butter with cheesecloth or metal strainer. Get as much moisture as you can out of the butter. You will be left with approximatley 2 cups of butter & 2 cups of buttermilk, which you can reserve and use in recipes that call for such.
Note that butter will expire when the cream would (unless frozen).