I used some baby food jars and heavy cream (I only left it out 4 hours--I got impatient). I filled the jars about half full.
The shaking! Took a few minutes.
This is when we knew we had butter.
Drain out the butter milk (note to self: save for pancakes).
Then we put the butter in a dish, mixed it with a bit of salt, and ate it on pancakes!
The kids enjoyed making it (once).