I made butter today. Yes, I made butter, as in butter for toast. I saw this video on YouTube and had to try it for myself.
I totally forgot to leave the cream out to let it sour so mine came out of the fridge, so it was cold. I was shaking and shaking and shaking for 20 minutes before it finally started to separate the butter from the buttermilk. My arms are now shaky and tired. But I did make butter! Since I didn't let it sour the butter is pretty plain tasting so I did add a little salt and it's a really nice homemade butter!! It's a light cream color and not the yellow that you see in store bought butters. Most of the yellow color in those butters are added coloring. There are some variations in butter colors depending on what the animal eats, but usually natural butter isn't super yellow.
Anyway, I think next time I'll let the cream sour. Having the cream at room temperature will make the process go much faster and the sour tang will give the butter and buttermilk some more flavor. I have to let my forearm muscles recover before I try this again.