How to make butter? Well there are plenty of methods but they all really involve doing the same thing.
You simply need to agitate the cream until all of the butterfat coalesces. This can be done with a churn, a butter maker, a whisk or even just a bottle that you shake.
It can even be done simply by accident as you whisk cream (not when you are using a whipped cream dispenser and cream chargers) this is the same action and indeed whipped cream could really be considered as half-finished butter.
To understand about how to make butter then you need to understand what cream actually is: it is a combination of fatty molecules and aqueous molecules – but there are all rather small so happily combine together.
By agitating the butter you cause the butterfat molecules to literally bang into each other and get bigger – as they stick the separate from the aqueous component of the cream (butter milk) and rise to the surface. The more you shke or whisk the bigger they become until all of the fat is a floating mass on the surface of the cream.
This is butter – you could stop here but it is importation to make sure it is pure so that it lasts longer than a few days before it goes rancid.