Silly Experiment of the Week:
Put Cream in Bottle on Mountain Bike. Go Have Fun.
Wash Dirt off Bottle. Observe lack of Solidity inside with Sadness.
Shake Exactly Twice; Feel Thud in Bottle. Wahoo -- Butter!
Rinse and Drain; Eat on Toast. Yum.
Next time: Use good cream from the Milk Pail. Perhaps fester on the counter overnight for flavor development before churning.