What You Do:

1. Warm the whipping cream to room temperature. It will work faster than if it is cold straight from the freezer. 
2. Wash you hands! 
3. Pour the whipping cream into the jar. Make sure you only fill the jar about half full. 
4. Add your marbles to the jar with the cream and tighten the lid so that it seals. 
5. Shake the jar back and forth for about 10-20 minutes. You can put on dancing music to keep the shaking fun. 
6. When the contents start to form yellowish clumps, you're done. The solid yellow stuff you see is butter. 
7. Pour the butter and liquid (Buttermilk) into a strainer. Set aside the buttermilk for tomorrow's pancakes or bisquits. 
8. When all the liquid has drained, rinse the butter (still in the strainer) with ice-cold water. 
9. Place drained butter in a bowl and add a little salt to taste, working it in well with a spatula. 
10. Put in the refridgerator to chill.