You can make it at home from heavy cream - it’s often been suggested as a ‘party game’:
http://www.youtube.com/watch?v=dxyla_OJKgA
http://www.thespruceeats.com/homemade-butter-in-a-jar-4155677
Yes, my third grade class churned some up after touring a local dairy. Spread the soft sweet butter on our graham crackers with whole milk....yum.
But the video is not about the churning it’s about processing the ‘raw’ butter...getting much of the water out and final hand shaping and finishing. The owner’s poetic commentary on the process is the cherry on top